Historically, a normal human population hovered on the edge of starvation.
It's hard to comprehend how important food staples used to be. In Edo Japan, wealth was measured in koku (石). One koku is (in theory) enough rice to feed one man for one year. The amount of koku a daimyo controlled was basically how many people he owned because a region's food staple production determined its carrying capacity and the human population grew until it hit carrying capacity. In other words, we bred until we were on the edge of starving to death. Most wars have ultimately been fought over land because land determines food production and food production was a matter of life and death.
Adam Smith expressed a similar sentiment in 1776. [Edit: The information contained in the below quote is of dubious veracity. See comment.]
The poverty of the lower ranks of people in China far surpasses that of the most beggarly nations in Europe. In the neighborhood of Canton, many hundred, it is commonly said, many thousand families have no habitation on the land, but live constantly in little fishing-boats upon the rivers and canals. The subsistence which they find there is so scanty, that they are eager to fish up the nastiest garbage thrown overboard from any European ship. Any carrion, the carcase of a dead dog or cat, for example, though half putrid and stinking, is as welcome to them as the most wholesome food to the people of other countries. Marriage is encouraged in China, not by the profitableness of children, but by the liberty of destroying them. In all great towns, several are every night exposed in the street, or drowned like puppies in the water. The performance of this horrid office is even said to be the avowed business by which some people earn their subsistence.
China, however, though it may, perhaps, stand still, does not seem to go backwards. Its towns are nowhere deserted by their inhabitants. The lands which had once been cultivated, are nowhere neglected. The same, or very nearly the same, annual labour, must, therefore, continue to be performed, and the funds destined for maintaining it must not, consequently, be sensibly diminished. The lowest class of labourers, therefore, notwithstanding their scanty subsistence, must some way or other make shift to continue their race so far as to keep up their usual numbers.
But it would be otherwise in a country where the funds destined for the maintenance of labour were sensibly decaying. Every year the demand for servants and labourers would, in all the different classes of employments, be less than it had been the year before. Many who had been bred in the superior classes, not being able to find employment in their own business, would be glad to seek it in the lowest. The lowest class being not only overstocked with its own workmen, but with the overflowings of all the other classes, the competition for employment would be so great in it, as to reduce the wages of labour to the most miserable and scanty subsistence of the labourer. Many would not be able to find employment even upon these hard terms, but would either starve, or be driven to seek a subsistence, either by begging, or by the perpetration, perhaps, of the greatest enormities. Want, famine, and mortality, would immediately prevail in that class, and from thence extend themselves to all the superior classes, till the number of inhabitants in the country was reduced to what could easily be maintained by the revenue and stock which remained in it, and which had escaped either the tyranny or calamity which had destroyed the rest.
—An Inquiry Into the Nature and Causes of the Wealth of Nations by Adam Smith
If you went back in time and asked an ancient person what a magical "post-scarcity society" looked like he or she would describe a world with lots of food.
And I am come down to deliver them out of the hand of the Egyptians, and to bring them up out of that land unto a good land and a large, unto a land flowing with milk and honey;
—Exodus 3:8 King James Bible
In ancient times, "post-scarcity society" meant a world with enough food for everybody. I buy 50-pound bags of rice for $50. If I ate nothing but rice it would cost me $450 per year. The US GDP Per Capita is $64,000. By the standards of medieval Japan, we have 100× the economic production of what people need.
Thrift stores throw away clothes more comfortable than all but the finest medieval silks. The Internet provides higher quality information and entertainment for free than anything available in the 1940s. Smallpox is extinct.
Our norm of what constitutes "basic life necessities" has expanded. It includes health care, meat, milk, sewage, soap, hot running water, education, Internet, cars and nice clothes—half of which were unimaginable to medieval peasants. The whole package can be bought for less than half the US per capita GDP.
We take for granted things that medieval kings would have considered effeminate luxuries, like whole buildings heated to spring temperatures year round. And if things go well, our descendants will take for granted things we would consider shockingly luxurious. There is no absolute standard for material wealth. Health care is a component of it, and that alone is a black hole.
―Why to Not Not Start a Startup by Paul Graham
The fact there is enough to go around doesn't mean it actually goes around.
If we flattened wealth inequality without destroying the economy AND we cured all diseases AND we invented cold fusion AND we established world peace AND population growth stayed low then we still wouldn't be producing enough value to exhaust interpersonal competition. Somewhere in the multiverse, a human-like species is employing slave labor to build a Dyson Sphere that mines cryptocurrency.
Even the citizens of Kardashev Type III civilization can't all date Emma Stone and/or Keanu Reeves at the same time.