A few things Inwant to say about this but first I want to put in the proviso that I think the top fighters should be getting paid more.
I don't know about your experiences as a kid but mine were that you took up whichever sport or hobby you were interested in and you enjoyed. At no point when I was a kid did I think- "Hold on....rugby is an amateur sport which doesn't pay and football(soccer) pays a mint. Fuck this rugby shit I'm footballing all day!"
That doesn't matter shit, what really matters was that I enjoyed playin rugby and I wanted to play it more. The same goes for every single sport. Some of which are still amateur today and continue to attract kids.
2. Making the issue of participation in a sport all about money is a bit of a narrow minded (i.e. retarded) way to think about it. Basically what you're saying is that until MMA pays the highest amount of money of all sports, something they will never do, then it will never attract top athletes?! Well, shit, we might as well pack in then because we're never going to get the top athletes.
3. You stated that top athletes like Bones Jones etc would not come to MMA because the money is better elsewhere. Guess what? The money in MMA is a fuck load better now than it was when Bones was in his impressionable youth and he's still fighting teh UFC!
In short, I agree that top fighters should get paid more. By that's because I think they earn it. The sponsors are investing in the sport because of the hard work that the fighters are doing to entertain us fans. Sure, the company deserve's a cut because they're working damn hard too but, presently, the fighters cut appears to be too small and the company's too large.
This is the only real argument in favour of higher fighter pay that I can think exists. All the others are just over-emotive rants or logic fails.