Around 2009, I embarked on being a serious amateur historian. I wouldn't have called it that at the time, but since then, I've basically nonstop studied various histories.
The payoffs of history come slow at first, and then fast. History is often written as a series of isolated events, and events are rarely put in total context. You can easily draw a straight line from Napoleon's invasions of the fragmented German principalities to how Bismarck and Moltke were able to unify a German Confederation under Prussian rule a few decades later; from there, it's a straight line to World War I due to great power rivalry; the Treaty of Versailles is easily understood in retrospect by historical French/German enmity; this gives rise to World War II.
That series of events is hard enough to truly get one's mind around, not just in abstract academic terms, but in actually getting a feel of how and why the actors did what they did, which shaped the outcomes that built the world.
And that's only the start of it: once you can flesh out the rest of the map, history starts coming brilliantly alive.
Without Prime Minister Stolypin's assassination in 1911, likely the Bolsheviks don't succeed in Russia; without that, Stalin is not at the helm when the Nazis invade.
On the other side of the Black Sea, in 1918, the Ottoman Empire is having terms worse than the Treaty of Versailles imposed on it -- until Mustafa Kemal leads the Turkish War of Independence, building one of the most stable states in the Middle East. Turkey, following Kemal's skill at governance and diplomacy, is able to (with great difficulty) stay neutral in World War II, not be absorbed by the Soviets, and not have its government taken over by hard-line Muslims.
This was not-at-all an obvious course of events. Without Kemal, Turkey almost certainly becomes crippled under the Treaty of Sevres, and eventually likely winds up as a member of the Axis during World War II, or gets absorbed as another Soviet/Warsaw Pact satellite state.
The chain of events goes on and on. There is an eminently clear chain of events from Martin Luther at Worms in 1521 to the American Revolution. Meanwhile, the non-success the Lord Protectorate and Commonwealth of England turned out less promising than was hoped -- ironically, arguably predisposing England to being less sympathetic to greater democracy. But the colonies were shielded from this, and their original constitutions and charters were never amended in the now-becoming-more-disenchanted-with-democracy England. Following a lack of consistent colonial policy and a lot of vacillating by various British governments, the American Revolution happens, and Britain loses control of the land and people would come to supplant it as the dominant world power one and a half centuries later.
Until you can start seeing the threads and chains of history across nations, interactions, and long stretches of time, history is a set of often-interesting stories -- but the larger picture remains blurry and out-of-focus. The lessons come once you can synthesize it all.
Hideyoshi Toyotomi's 1588 sword hunt was designed to take away weapons and chances of rebellious factions overthrowing his unified government of Japan. The policy was continued by his successor after the Toyotomi/Tokugawa Civil War, which leads to the Tokugawa forces losing to the Imperial Restoration in 1868 as their skill at warfare had atrophied; common soldiers with Western artillery were able to out-combat samurai with obsolete weapons.
Nurhaci founded the Qing Dynasty around the time Japan was being unified, with a mix of better command structures and tactics. But the dynasty hardened into traditionalism and was backwards-looking when Western technology and imperialists came with greater frequency in the late 1800's. The Japanese foreign minister Ito Hirobumi offered to help the Qing modernize along the lines Imperial Japan had modernized while looking for a greater alliance with the Chinese. But, Empress Dowager Cixi arrests and executes the reform-minded ministers of Emperor Guangxu and later, most likely, poisoned the reform-minded Emperor Guangxu. (He died of arsenic poisoning when Cixi was on her deathbed; someone poisoned him; Cixi or someone acting under her orders is the most likely culprit.)
The weak Qing Dynasty starts dealing with ever-more-frequent invasions, diplomatic extortions, and rebellions and revolutions. The Japanese invade China a generation after Hirobumi was rebuffed, and the Qing Dynasty entirely falls apart. After the Japanese unconditional surrender, the Chinese Civil War starts; the Communists win.
From this, we can start drawing lessons and tracing histories, seeing patterns. We start to see how things could have broken differently. Perhaps Germany and France were doomed to constant warfare due to geopolitics; maybe this is true.
But certainly, it's not at all obvious that Mustafa Kemal would lead the ruins of the Ottoman Empire into modern Turkey, and (seemingly against overwhelming odds) keep neutrality during World War II, rebuff Stalin and stay removed from Soviet conquest, and maintain a country with secular and modern laws that honors Muslim culture without giving way to warlordism as happened to much of the rest of the Middle East.
Likewise, we can clearly see how the policies of Empress Dowager Cixi ended the chance for a pan-East-Asian alliance, trade bloc, or federation; it's not inconceivable to imagine a world today were China and Japan are incredibly close allies, and much of the world's centers of commerce, finance, and power are consolidated in a Tokyo-Beijing-Seoul alliance. Sure, it's inconceivable with hindsight, but Japan in 1910 and Japan in 1930 are very different countries; and the struggling late Qing Dynasty is different than the fledgling competing factions in China after the fall of the Qing.
We can see, observing historical events from broad strokes, the huge differences individuals can make at leveraged points, the eventual outcomes in Turkey and East Asia were not-at-all foreordained by geography, demographics, or trends.
Originally, I was sketching out some of these trends of history to make a larger point about how modern minds have a hard time understanding older governments -- in a world where "personal rule" is entirely rebuffed in the more developed countries, it is hard to imagine how the Qing Dynasty or Ottoman Empire actually functioned. The world after the Treaty of Westphalia is incredibly different than the world before it, and the world before strict border controls pre-WWI is largely unrecognizable to us.
That was the piece I was going to write, about how we project modern institutions and understandings backwards, and how that means we can't understand what actually happened. The Ottomans and Qing were founded before modern nationalism had emerged, and the way their subjects related to them is so alien to us that it's almost impossible to conceive of how their culture and governance actually ran.
I might still pen that piece, if there's interest in it -- my attempt at a brief introduction came to result in this very different one, focused on a different particular point: the threshold effect in learning history.
I would say there's broadly three thresholds:
The first looks at a series of isolated events. You wind up with some witty quips, like: Astor saying, "Sir, if you were my husband, I would poison your drink." Churchill: "If I were married to you, I'd drink it."
Or moments of great drama: "And so the die is cast." "Don't fire until you see the whites of their eyes." "There is nothing to fear except fear itself."
These aren't so bad to learn; they're an okay jumping-off place. Certainly, Caesar's decision to march on Rome, Nobunaga's speech before the Battle of Okehazama, or understanding why Washington made the desperate gamble to cross the Delaware all offerlessons.
But seeing how the Marian military reforms, Sulla's purges, and the Gracchi brothers created the immediate situation before Julius Caesar's fateful crossing is more interesting, and tracing the lines backwards, seeing how Rome's generations-long combat with Hannibal's Carthage turned the city-state into a fully militarized conquest machine, and then following the lines onwards to see how the Romans relied on unit cohesion which, once learned by German adversaries, led to the fall of Rome -- this is much more interesting.
That's the second threshold of history to me: when isolated events start becoming regional chains; that's tracing Napoleon's invasion of Germany to Bismarck to the to World War I to the Treaty of Versailles to WWII.
Some people get to this level of history, and it makes you quickly an expert in a particular country.
But I think that's a poor place to stop learning: if you can truly get your mind around a long stretch of time in a nation, it's time to start coloring the map. When you can broadly know how Korea is developing simultaneous with Japan; how the Portugese/Spanish rivalry and Vatican compromises are affecting Asia's interactions with the Age of Sail Westerners; how Protestantism is creating rivals to Catholic power, two of which later equip the Japanese's Imperial Faction, which kicks off the Asian side of World War II -- this is when history starts really paying dividends and teaching worthwhile lessons.
The more you get into it, the more there is to learn. Regions that don't get much historical interest from Americans like Tito's Yugoslavia become fascinating to look at how they stayed out of Soviet Control and played the Western and Eastern blocs against each other; the chain of events takes a sad turn when Tito's successors can't keep the country together, the Yugoslav Wars follow, and its successor states still don't have the levels of relative prosperity and influence that Yugoslavia had in its heyday.
Yugoslavia is hard to get one's mind around by itself, but it's easy to color the map in with a decent understanding of Turkey, Germany, and Russia. Suddenly, figures and policies and conflicts and economics and culture start coming alive; lessons and patterns are everywhere.
I don't read much fiction any more, because most fiction can't compete with the sheer weight, drama, and insightfulness of history. Apparently some Kuomintang soldiers held out against the Chinese Communists and fought irregular warfare while funding their conflicts with heroin production in the regions of Burma and Thailand -- I just got a book on it, further coloring in the map of the aftermath of the Chinese Civil War, and that aspect of it upon the backdrop of the Cold War and containment, and how the Sino/Soviet split led to America normalizing relations with China, and...
...it never ends, and it's been one of the most insightful areas of study across my life.
History in that first threshold -- isolated battles, quotes, the occasional drama -- frankly, it offers only a slight glimmer of what's possible to learn.
Likewise, the second level of knowing a particular country's rise and fall over time can be insightful, but I would encourage anyone that has delved into history that much to not stop there: you're not far from the gates unlocking to large wellsprings of knowledge, a nearly infinite source of ideas, inspiration, case studies, and all manner of other sources of new and old ideas and very practical guidance.