Also since we are talking about aspirations you have to consider the "all or nothing" attitude that's so common these days, and I see a lot of people particularly in the lower classes who are far more motivated about the tiniest possibility of a quick jackpot than a slow but steady improvement in their lives.
But then again that way of thinking might have more to do with the way the middle class (the "steady option") is disappearing than with a social fad.
I agree that it sucks to be poor, but I don't know how much startup funding can fix that.
For starting and running a startup, maybe, but those forces are much less in effect when the upper classes are doing the hiring. As we see at a lot of these companies, they aren't really reaching very far outside of their cohort. Cue the culture-fit debate.
I think aspirations are likely to play a big role here, after all people tend to judge their successes relative to their family and close friends. So for a kid from a poor neighbourhood (who's more likely to be black), getting a good job with a decent salary and benefits is a great success already and running a startup is too risky so there's less incentive.
If you come from an upper middle class family and all of your siblings are training to be lawyers or doctors then that ups the ante a lot in what your "floor" to success is, and like you say risk is reduced because of family so starting "the next facebook" looks like a more attractive option.