It might seem odd to call politics undervalued. But if we want to think about how to improve matters for millions of people, it's clear that effective governance and institutions which promote human flourishing are extremely valuable. One example is the Jin dynasty: in between the end of the Han dynasty and the rise of the Jin, the Chinese population dropped by 4/5ths. The wars immortalized in Romance of the Three Kingdoms ere the deadliest before WWII. The existence of any halfway competent central power would have spared millions of people.
Closer to home housing policies in the Bay Area force the poorest in society to spend vast sums to keep a roof over their head. Poor educational opportunities reduce the ultimate earning potential of millions. In some cases, such as pollution controls, the costs of poor policies are measured in lives.
Many people enter politics, and competition is tough. But many opportunities exist that are frequently underexploited, such as school boards, transportation boards, and down-ticket positions with considerable power. Often these positions are dominated by people without an understanding of the issue, and subject to heavy lobbying from those who are directly involved. Occasionally important policies are made in relative obscurity: who here knew about the raisin price controls before it came before the Supreme Court?
There are many ways in which politics might be affected. One is through political theorizing. Robert Bork's The Antitrust Paradox influence a generation of judges and policymakers, leading to a radically different antitrust policy in the US, which benefited consumers. Milton Friedman was the handmaiden of a major shift in economic policy in the US. On the other end Sayyid Qutb has been blamed for the rise of Islamism, which has made life a great deal less pleasant for many people around the world. However, the returns on political theory are extremely uncertain: many works of political philosophy go ignored.
Another is through political organizing. Here the model is the Social Democratic parties of yore, which had profound effects on the social institutions of the countries in which they operated. To the extent the poorest in Europe are better off because of these parties, this work directly improved people's lives. Unfortunately, there is good reason to suspect this is much less doable today.
A third is through competent leadership. Many municipalities are governed poorly for a variety of factors. Publicly minded citizens with slightly better than average interest should be able to copy good policies into poorly governed cities. Many bad policies are the result of rent-seeking, which can easily be resisted, at the cost of having resources for reelection.
Politics inherently involves leverage. Decisions about policies affect all those in a jurisdiction where the policy applies, and can have knock-on effects, such as financial regulation in a major finance center, or the impact of California emission standards on automobiles. Furthermore, good institutions can last for centuries.
At its most extreme, decisive political action has changed the fates of millions. At its least extreme an effective mayor can ensure that children are educated, potholes repaired, and new housing built. In between politics may offer the best leverage of any opportunity for altruism.