I couldn't find an exact number for fighters under UFC contract, but I think it's less than 200.
Guess again. And yes, despite the url that list is up to date as of four days ago.
EDIT: Fuck; beaten.
I do agree with your overall point though.
They should just give straight monthly stipends, on top of purses. Let the fighters decide how to spend them. Also your average fighter fights twice a year, because that's how many spots are available on cards. Some fight less, either because they get injured or because some people manage to get booked more.
Anyway, let's put it at $2000 a month, on top of their purse money. This is not a living wage for most fighters, but sure as fuck helps, and it'd be a predictable income.
$24k * ~540 fighters = $12,960,000.
You have a healthier pool of fighters who are going to be far less likely to end up financially unable to stay in the fight game despite winning a title eliminator in their final fight (TJ Grant) or homeless while actively under contract (Patrick Cummins). The stipend is also another thing a fighter can lose if they piss hot, so all the more motivation to stay clean.