It's a struggle out there.
There was a saying back when I played.
"live in futures die in futures"
If you dont make it out of the futures and challengers circuit by grinding through or wildcards, your going to be most likely stuck there, unless your winning them left and right.
I had a friend who went through the futures, got a point and had a world ranking (in the 1000's) but he didn't go through the USTA backed academies, never got any wildcards, no help from the USTA at all.
He burned all his money paying for flights and food in different countries.
He eventually had to call it quits, he couldn't afford coaching, travel, and equipment costs on a tennis coach's wages. He didn't come from money so his talent was wasted.
He did tell me stories of some players who would throw matches against players they knew, since some of them were sponsored it didn't matter if they lost, they were helping that friend out by letting them advance to the next round.