Check it out: Promoter Breaks Ties with Pro XCT Series.
Get average sport and beginner racers (and folks who have never raced) psyched about racing these events, and you'll have money for prizes. Nobody is going to pay to watch, it's a participant sport. Sponsorships only cover so much. As a promoter, your income is going to come from entry fees - so the more riders have a great time and come back next year, the better you'll do.
Spend all your time and money kowtowing to the UCI and USAC (and ignoring the amateurs), on the other hand, and you'll end up with 20 "pros" vying for a big steaming pile of nothing while a few disinterested spectators and the occasional parent stand around the finish fencing looking bored.
It amazes me that USAC hasn't figured this out. F*&$ the Olympics - I want to see a full field in the women's junior beginner. THAT is when you'll be able to make a living racing a mountain bike.