The top UFC fighters can make quite a lot of money for a single fight especially if it is such a big deal that it's televised on Pay-Per-View. For the guys at the top, they might be looking at a base salary of a few hundred grand for the win, plus thousands more in knockout bonuses or "fight of the night" bonuses, and potentially hundreds of thousands more in "back room" bonuses. These guys are also probably going to have a number of sponsorships or endorsement deals. At the end of the day, they may be taking home more than a million for a single fight—not as much as a boxer at the top of his game, but still not bad. However, those are the exceptions rather than the rule.
Below them you have your second-tier fighters, bringing in between $10k-$25k per fight. But most likely you will work like the devil to book a fight once every few months, for which you will get paid a few grand, plus another few grand if you win. Not to mention the fact that this doesn't include money taken off the top for insurance, licenses, taxes, manager/promoter fees, etc. Considering how hard it is to make a buck doing this, it doesn't make much difference whether you're a lover or a fighter. Both pay roughly the same.