No.You'll almost certainly not get rich in MMA. If you're really good, you can have a decent living, support a family, etc. A lot of MMA fighters, though, have full- or part-time jobs to supplement their meager income from MMA.
According to the latest report by Celebrity Net Worth, McGregor is the richest UFC fighter in the world. Not just in combat sports, the net worth of McGregor makes him one of the richest athletes in the world. Interestingly, he held the 35th spot in Forbes' list of The World's Highest-Paid Athletes in 2024.