But that's exactly the problem.
20-something's shouldn't be wasting their time on things that, with a mature person's wisdom, aren't worth risking their time on. Rather they're better off gaining experience so they have good judgment when they're 40-something.
And 40-something's can handle it with a family and mortgage, because they're not naive enough to think you need to live on ramen to make it big. No: they have connections, put together a team, raise capital like the professionals they are, and continue to pay themselves a salary that can support a family.
Having an appetite for risky things is dumb. Isn't there a quote somewhere about how successful businessmen don't take risks? They try to only do things that seem to be a sure bet, and try to only use other people's money.