At least with Donald Young, he had one junior world tournaments and it looked like he was the future. I could understand guys like him and Agassi and Sampras.
With these guys, just breaking the top 200 would be an accomplishment. And there really isn't much money until you break into the top 100.
Most will have quit long before then due to financial concerns. And then you're looking at trying to get a job with no degree. Guess it's ok if you're feeding balls to little old ladies, but that's fairly limiting for most.
Wayne Odesnik, #134 in the world, made $49,838 so far this year.