I'm another one of those CPers that stayed around.
If your question is... how many CPs stay with Disney, the percentage is pretty small. Especially considering that the CP has more than 6,000 participants at any given time.
But if your question is... how many CMs started out on the CP, then the percentage is much larger! I would say, from my experience, about half of CMs were CPs first.
Here is my path, just under 4 years:
CP - PI - FT (Merch) - TA O&T - TA Salaried Consultant - TA Leader - FT Leader
As for the money, anyone in the hourly role (either front line or O&T) are not there to make money. They love making magic or they are trying to work their way up.
I'm a new Manager (so on the lower end of the pay scale) and my salary is quite comparable to what I'd be making with my degree. Granted, my Masters is in Education, so not really a field that makes much money anyway. The 24K guess above is very low. DH and I live very comfortably and both work for the Mouse.
On another note - some hourly roles do make more than their Managers. A good friend of mine was well trained in his area, so was extended a lot, came in early the next morning, and essentially lived on OT and Double Back. He was promoted to Manager, where he spent a couple months, but then stepped down because he needed the extra OT income. He works a lot more hours than I do, but in turn does make more at the end of the week.