Without doing much thinking or reading on WHY they think it, I'm fairly sure a lot of it boils down to their misunderstanding of "nature" and more specifically the "nature of man."

John Locke + Darwin = chud brain basically.

They believe people in a "state of nature" are ruthless beings where might is right and through this competition for resources (and this is where a lot of gross fantasies come in ie Jordan Peterson now days and many others) innovation happens and that innovation eventually led to where we are now. To cooperate would be anti-nature according to them.

So, I don't want to write a book here, but to keep it brief. They're wrong. On all accounts.

Firstly they do not understand nature in general much less human nature. Competition exists in nature, but there is also an entire fucking field within biology that studies mutualisms, etc. (my undergrad degree is in biology. So, not an expert, but I know too much).

To act as if all of nature is constantly killing each other is stupid. It's baby-brained even for Locke's day. They also misunderstand Darwin and evolution in general. Evolution isn't a conscious process and you cannot impose upon a species arbitrary restrictions and surpluses and whatnot and assume "this will lead to this." Because that's not how it works.

To expand into their idea of applying a broad concept of Darwinism to society they believe forcing a state of competition (which kind of gives the game away... they FORCE it to exist) will cause "weak" people to naturally come to be ruled by the strong and, given time, either the weak will all die out or the strong will subjugate them. It's a bleak worldview and basically was created post hoc as a way to justify a lot of what Europeans then and now did to other groups of people.

Societies (key thing here) are built, by definition, on cooperation and implied and explicit norms, customs, laws, etc. If there is any "natural state of man," which I reject the premise of as stupid, it would be small groups of humans working together to survive and sometimes gathering into larger groups. A single human though, the individual, would die. Humans are capable of amazing feats when we work together but when we're apart from society on our own we are soft, slow, weak, and will be overcome very quickly. Something which many FREE MARKET LIBERTARIANS ™️ like to forget.

Capitalism basically seeks to reproduce a mythological time where individuals roamed the savannas and created things to outsmart the other humans... who then died (kind of key to their fucked up worldview. They just want everyone except them to die). It ignores the real, observable nature of humans (cooperation) and seeks to pretend that humans would be (or are) most productive when their lives are stressed and constantly in danger. The times when people lived closed to what they idealize would be those savanna days when technology was low. Before agriculture was discovered and led to large cities. And that time period from the branching off of Homo sapiens from our ancestors up until the building of cities based around farming was a looooong time full of nearly zero innovation. It wasn't until humans settled, became farmers, got comfortable, and truly cooperated that we began to truly innovate.

This is the fundamental fallacy in their thinking. What they want, constantly living on the edge, does not lead to new technologies. Living in comfort with free time for everyone, discussions, education, spreading of ideas, synthesis of ideas, all that stuff, very obviously I think, is what leads to innovation. Not being forced to work 12 hours a day or more anymore than being forced to walk 12 hours in a savanna chasing a wounded animal. Neither of these humans has time to create shit. And their suffering doesn't forge stronger humans who create new stuff. It might make for a harsher society, one where might being right is easier to justify though. And that's kind of the entire goal. They want to believe and justify their cruelty and the position they ended up in is just and natural when it is not. They (or their ancestors) worked against the cooperative nature of humans, exploited them, and now they seek to explain their actions as "natural." That's where you get insane racists talking about "manifest destiny" and all the other type of shit. It's all just a way to explain away anti-social behavior. And capitalism is, basically, a way to formulate an entire society around that coping mechanism. Just tell everyone if they exploit someone else harder then they will rise to the top. It's all very gross and people who justify it when its laid bare are the worst demons on earth. They end up being the types to justify starving entire nations for whatever bullshit reason they concoct.

Comrade Yugopnik made a video that explains why and how

They love living in the edge of homelessness

Not just a race, but a full throttle sprint that gets faster and faster

In which book does he do that?