Throughout 99% of human history, the economy was mostly zero sum. If someone was rich it was because they stole it. If a group was wealthier it was because they stole it. By "stole it" I'm including theft of labor through slavery as well as the usual conquests and raiding. There was little to no innovation over time spans as long as thousands of years.

Most of human culture and philosophy evolved during these periods and bakes in the idea that the pie is finite and that anyone with more of it has stolen it, because that was just an accurate picture of reality.

A growing pie is a rare condition. It has happened a few times during periods of high civilization: Egypt, Greece, and Rome in the West and similar examples exist in lots of other places.

A rapidly growing pie is entirely new. The modern world is an extreme historical aberration built on the scientific method, modern engineering methods, and the discovery of massive amounts of exploitable cheap energy in the form of first fossil fuels, then nuclear power, then (today) learning to exploit things like solar and wind energy at exponentially larger scales. Other innovations that have fed into this unique condition include synthetic fertilizers, antibiotics, vaccines, etc.

Humans have never lived in an environment like this. Everything in our evolution and our accumulated culture is screaming that it's wrong -- that it will either collapse tomorrow (hence the perennial popularity of doomerism) or that it must be built on some kind of insanely massive crime because otherwise where is all this wealth coming from? That's because it's impossible. It cannot be. The idea that wealth can be created at this scale is just... not a thing that has ever existed until maybe 200 years ago max but really more like 80-100. Before that there was only subsistence and theft.

Edit: I'm not arguing that there is no slavery or near-slavery or theft/conquest in the modern world. These things certainly still happen. I'm arguing that it is not the primary source of our massive wealth. Slavery and conquest have always been around and no society has ever been this wealthy or grown this fast. Not even close.

You're ignoring inflation. Real (inflation adjusted) median earnings are up 12%, in total, over the past 45 years. [1] That also understates the problem because many things (education, healthcare, debt costs, etc) are understated or not even considered in inflation measurements. There's also been a substantial increase in baseline necessities for the average person (internet, computing device, etc). Factor these in and it's fairly safe to say that real incomes have declined for the majority of people.

Similarly a lot of our wealth is just a facade. Most of it derives from the stock market, yet the market cap of the stock market is now dramatically larger than all of the money in existence. Consider that the system that created this mess only started in 1971 (the end of Bretton Woods) and it already only being propped up by ever more extravagant financial games. The house of cards is likely to come down without our lifetimes, which will make this one of the shortest lived economic experiments, and failures, ever. 'Doomerism' isn't a response to the growth, but to the increasingly unstable fundamentals underpinning everything, let alone in an era that's also an obvious geopolitical inflection point as well.

[1] - https://fred.stlouisfed.org/series/LES1252881600Q

I think what you are missing is that wealth is actually just "motivation to do work" in quantifiable pieces (we call it "currency", and mark-to-market assets for convenience).

If I could bake a muffin that would make you effortlessly glide through, say, a full day of perfectly laying bricks without taking a break, a warehouse of those muffins would mean I'm extremely wealthy. No money, markets, or currency necessary. It's the purified extract of wealth.

With that in mind, you can see that there is still huge room for more wealth creation. The majority of humans are still doing work that doesn't motivate much work from other humans.

I would hazard a guess that a lot of the so-called wealth is not actual, directly owned material wealth, but immaterial numbers: indirect, abstract proof of ownership — in Baudrillard jargon, simulacra of ownership. Numbers, which, due to their illiquid nature and their disconnect from material ownership, cannot be instantly and fully redeemed without sacrificing most of their purported value.