Not to sound like a stuck record for this thread, but the money had a big part to do with it, but also the fact that they weren't just doing it to get rich, but most fighters would have had to fight an awful lot of fights to get anywhere near any real money. And that means they would have been fighting on an evening, and then probably back at some backbreaking job the next day.

I see a comparison in rugby, where although the players are faster, stronger and more focussed since it went professional, the tougher guys were in the past. And the second thing that contributes to older guys being tougher is that they didn't have the option of backing out, or taking a few weeks off if they got injured, they had to do the buisness whatever, whilst today's top fighters can just take a few months off to try and keep themselves at peak condition.