IMO, the top three are:
#1 - They send it "home" (to a family member). Many of them have kids back home that someone else is raising. That $$ often goes to take care of the kid. Sometimes it goes to pay for a mortgage on a house back home. I also know some girls who family basically pushed them out-the-door to go do lucrative massage work in the US.
#2 - Some do salt it away for their own biz or retirement
#3 - Others do piss it away. Some girls really luv the casino. They are also good little consumers who go gaga over expensive, name brand items (Vuitton handbags, Omega watches, etc.).
Very few girls live high on the hog. Most live very, very sparsely. If you've ever seen their digs in Flushing, you know what I mean. Shitty public housing with 3-4 girls per apartment. They mostly take the bus everywhere. Almost all of them plead poverty, but not sure I buy it. Their living expenses are minimal and they pay almost no taxes. But if they are faithfully doing #1, then I can see them being broke all the time. If they start their own biz, then you will probably see more trappings of success, including some kind of German luxury car.
@mikemendez - I do know one superstar provider who definitely made over $100K a year, in fact, I'd guess about $300K. And she told me as much. Her body did hold out for more than a year, but after 5 years in the biz, her libido seems to have cooled. I know of others who I'd guess make around $100K per year based on volume and tip level they demand.