Yeah it's possible, what you need is to find a sponsor and that may be difficult. I've read somewhere that it took Michael Goulian almost 20 years to do that. Basically to find a sponsor you need to show that you know what you're doing, to do that you need to win a few competition, to do that you need to find a way to fund all your own training and get a competitive airplane.
To answer your question about who else does it full time...just a few from the top of my head, Rob Holland (as you said), Sean Tucker, all the Red Bull pilots, Skip Stewart, and a whole bunch of others.
Regarding how much they make, look at Kirby Chambliss' house, N32°34'17.84" W111°43'34.63", and a list of planes he owns:
http://www.redbullusa.com/cs/Satell...Off-the-Planes-in-His-Garage-021243108056027.