Great article, Matt.
The notion that fighters are making their money on "one night" is rather ridiculous, however. This does not take into account the 6-8 weeks of training prior to the bout, nor obviously, a lifetime of training in the martial arts.
Second, their actual income is their sponsorship money, purse, plus any PPV revenue (extremely unlikely except for a a few superstars) minus
training expenses. In the case of a mid level contender such as those mentioned, they're making about as much as a retail store manager, perhaps a regional manager.
Except for a handful of top tier guys: Lesnar, GSP, Liddell in '07, most guys are doing this because they love to fight.