Yeah, I don't think he is risking much from that particular opponent. I mean anything is possible but still. If he has survived this long taking head shots from the hardest punchers on the planet over and over, I wouldn't worry about this Paul fellow.I agree that is a valid comparison. The difference is that they are not risking permanent brain damage from a single punch. Worst case scenario is that Mick will need a hip replacement.
They have polls athletes and a disturbing amount would hypothetically take 5 years off their life to be a winner. The thrill of competing and winning, the roar of the crowd. I would guess that is what is driving him. Much like how it is very believable that he is a rapist, it is very believable that he is getting into the ring for not the money purposes. Consider the drugs bodybuilders take and even at the top ranks, they money really isn't there unless you go gay for pay, and you don't need to be on the top to ahem... top in that field.