500k profit a year (which is still good!) often means 5 mil/yr revenue. Considering the years of work, super high stress, lack of support network common to this, and generally bootstrapping from their own funds?

That is decent, but considering all those factors, far from a huge win. If they had put similar work (with the same skill set) into a normal job, they would likely have similar returns with less risk.

Especially since there is large ongoing risk of market shifts or the like making it fail with no warning in the future, and at least working in someone else’s enterprise they wouldn’t have their capital at risk.