That's not accurate, and either way it's irrelevant to the point.
If the UFC incurres expenses, marketing costs, runs ads, pays lawyers to spend time on contrasts, pays match makers to put together offers, they are incurring costs for every fighter they sign. The fighter can decide to produce 0 retun on investment, and exit the contract at the end of term.
So my question is would you be willing to sign a contract that absolutely costs you money for which the other party can deliver on as much or as little as they see fit and exit as if they had fulfilled their commitments. It's pretty straight forward.