This does make the assumption that the parents are doing well enough to be able to support their adult children. There are some situations where the parents need the support of adult children, instead of the other way around.
Regardless, "smart, sustainable work that will support my family" doesn't really map to the intentionally-accelerated make-or-break pace of most incubators and funds. Nor do those programs naturally align with founders who want to create a solid long-term business working from sound operating fundamentals (positive cashflow, measured and even conservative hiring, working to the team's strengths) instead of chasing the next exploding market and "faking it until you make it".
Coincidentally those safer, longer-term plays are also the ones most likely to actually build generational wealth and financial independence for people starting without either. The lack of a safety net (or the presence of one that you're thoroughly entangled in for others' sake) makes all-or-nothing, giant bets far less tenable when you aren't effectively free from having to worry about mundane details like housing or medical costs. That in turn discourages if not de facto shuts out both the least privileged and those with meaningful resources but too much to lose if it all goes wrong.
One has to be either dirt poor or very unlucky not to he able to move back with relatives. This sound like an excuse.
Yes - most people might be able to move back in with relatives, but among those people who can't, minorities are almost certainly going to be overrepresented, which was OP's point.