You mentioned that YC founders get paid a salary, so it doesn't seem like they're taking an outsized risk compared to early employees. Small business owners who take out SBA loans are the ones taking big personal risks, not founders of venture-backed companies.

The way I perceive it to work is that VC firms have funds to invest in new businesses[1], but they don't have ideas. They pay founders an outsized fee for their ideas when those businesses become successful. They don't have to pay outsized fees to early employees since those early employees are just interchangeable implementers.

They can attract those implementers with salaries lower than the prevailing wage since the excitement/casino factor is paying the wage delta.

This idea that early employees are interchangeable implementers is probably objectively true, but I don't consider it to be a particularly fair way to run society. If I was starting a cupcake truck with my friends they wouldn't be my friends anymore if I decided I deserved 50x their equity share just because I thought of the idea, even though they put in the same labor and capital I did.

[1] As a sidenote, I think it's perfectly fair for the VCs that do the funding to maintain an outsized amount of company ownership, as they are funding the venture's existence in the first place. But the founders themselves aren't doing that.