Stepping into the octagon demands lots of courage whatever your size, skill level and experience is, and whoever your opponent is, so doing that the most times on the highest level against people that would be considered as trained assassins in any time in history besides ours is possible only for the baddest of the bad, the toughest of the tough, the hardest of the hard.
You don't get to 25+ bouts without being pretty good, nobody in their right mind would even get into a ring that many times if they had no chance of coming out of it with their hands up, victorious.