The problem is the top earners won't complain. And they're the ones that have the power to make things change. Ngannou is probably the only active high profile fighter we have seen go against the UFC.
Those lower on the totem pole can't really do anything about it. They can go against the UFC but the problem is they signed a long term contract and have no leverage for re-negotiation.
We often hear Dana say, ''All the fighters are free to do whatever they want. You don't think we pay you enough to fight? Then don't fight''. What he doesn't tell you is he won't let them fight elsewhere.
So they have 2 options.
1. Get a regular job because they can't pursue their passion in another organization.
2. Fight out their ridiculously long contract.
The UFC is a well oiled machine.