This is what happens when you sign a contract. This is capitalism, not socialism. There's no profit sharing.
Doesn't matter if you make your company $1 billion; if you signed up to make $5,000 then that's what you are going to make.
What about the retired actors and singers who are starving but companies are making $100s of millions using their likeliness, old movies, or music because they sold the rights away? That's capitalism. They don't get paid because they didn't negotiate properly.
Nobody "deserves" anything; just a fact of life in a capitalist society.
We also have to remember that what they report out as the fight contract amount if often much less than a fighter makes off other income such as sponsors (ever see how many sponsors they have on their shorts and banner) appearance fee, endorsement, etc.
I know there is some serious cash in this sport at the higher levels from various sources.
No one is going to get rich in an entry level position particularly in this depressed economy.
I do think the UFC could afford to pad some of the undercard fighters salaries some.