I don't believe that prossies 'earn' that much in the first place. My experience is that when I want to see a prossie I can see her at the time I request. If I need to change the time, guess what? They can also accommodate that. So their hourly rate might be high, but I suspect only a minority actually 'work' many hours. It's still bloody good money, given their education and alternative prospects, but it isn't enough to become rich.
A prossie's arse is a depreciating asset (arse-et?
). Yes, there is a market for the older prossie, but it's a much smaller market. So even those who do generate a lot of money can only do so for a short period of time.
So we're already talking about a minority of prossies who even have the prospect of becoming a millionaire, and of those only a tiny minority would have the business sense to do so.