I mean, iphones are made by slave labor but I still have one. It's not going to stop me from watching the fights, but it always leaves a bitter taste in my mouth when I see a bad injury and realize that the fighter is pretty much screwed for life once they stop fighting.
It's a free country, sure. But that doesn't mean corporations and sports organizations are exempt from ethical employment practices. But they won't until they're forced.
You know what the UFC will say when the issue finally gets headlines that they can't squash? Dana White: "Oh great, if we provide health insurance to the fighters then the pay-per-views will cost $200 a card!"
ie. he'll just co-opt the generic discussion that comes out whenever people bring up the raising the minimum wage, or anything to do with workers' rights. The real answer is it will cut into their profits, and if they choose to recompensate that loss by reducing payouts or increasing payperview costs that's their choice. The PFL has already shown that a more ethical business model with larger fighter payouts can still be profitable and competitive. This is just the UFC being shitty.
But the UFC will run PR campaign to pit fans against fighters -- just like they do whenever a fighter develops business sense. Then the fighters that speak out will be afraid lose their fanbase and advertising deals, and not form a union. The ones without large fanbases or advertising deals (ie. minor and retired fighters) will continue on, but public support will wane without major fighters behind the movement. It would have to be someone with Conor McGregor type popularity at the height of their fame to even get the UFC to budge a little.
The reason the UFC's gameplan on this is so clear is because those are the exact cards the NFL, NHL, MLB and NBA played to delay the inevitable before they each were forced to finally take care of their athletes. The UFC won't shirk tradition.