There are so many problems with this line of logic. First off you are not a professional fighter and could never be one so your boasting that you would take the 8k/8k is irrelevant since you don't have the skill/talent/body etc etc to get hired to cage fight for that money. IF YOU DID and you were doing awesome knocking guys out in a cage on live teleivison/PPV you would quickly realize your worth and start to feel like a moron for doing all of that work, for contributing to the wealth of the UFC, and only bringing home an average jobs worth of money because that pay check you get is also what you use to pay for the training/management that you received. So that 15-20k check will end up being less than 10k.
Only a fool would be ok with being paid that for what you are doing. Not to mention all of the bodily harm that you have incurred, the concussions and broken bones. The physical issues that the UFC isn't going to cover all of because they already treated you after your fights but some of those ailments never actually go away, so you need advanced medical care all of the time and the UFC doesn't even provide real health insurance.
In the end no one wants to pay money to see you get KO'd in 5 seconds so your critique of these amazing fighters is ludicrous.