oh, make no mistake, i think MMA fighters are better athletes, due to the nature of their training.
Ill make a comparison thatll get me lots of shit from Sherdog - I also think Crossfitters, yes, Crossfitters, are better athletes than either olympic weightlifters or olympic distance runners. This is due to the nature of their training. The weightlifters have nearly eliminated their cardio and slow twitch muscle fiber, the Kenyans (yes, there are others) cant carry a bag of groceries for an old lady.
The reward for specializing is a small % payoff in comparison to the cost overall. You see a guy like Froning or Fraser get 400 overhead, and he is a high % of a world class weighlifter of the same weight. He can still run a 5k in 20minutes, which is a damned ways off a Kenyan, but itd win local running events, or place quite high, depending on who shows up. The Kenyan has trouble with the bar, and Pyros Dimas’ huge quads and hours of specialized training is gonna gas him out hard. Fraser is a better athlete. as is the decathlete, say Ashton Eaton, who wouldnt qualify for the Olys in any one of the ten events he spreads his training around.
But the thread question was, “which sport is harder to make it in?” there are countries with programs that are heavily funded and driven nehind those two other sports, and big rewards and acclaim for potential athletes. It is harder to make it in either sport, and in fact, one must be genetically made for it - whereas mma or crossfit allow a wider variety of bodytypes.
Crossfit pays shit, so it's mostly guys who didnt succeed somewhere else (although that is changing, i think) A guy who trained in his garage won four years ago. Its easier to make it, because less people are trying to win at it. You get more repeat champions in a sport like that. Decathlon is different because there are as many vying for that podium as there are in the other two olympic sports (i would guess)
Boxing pays more. If you are good at it, you would be crazy to not pursue it in favour of mma. so more people want that pie. If you cant make it and you have some wrestling, mma is a good backup.
side note - Dana White has put mma back. You cant own your own brand like a boxer, or mma fighter pre reebok deal, and the money just isnt there
unless you are a yappy cunt, which is why everyone is trying that angle. all the guy i ever trained with are like Fedor or Couture - softspoken, modest, good men. but people bend to the money, as would i.