Competing in a fistfight, barechested inside a chainlink fence in front a crowd of raucous onlookers isn't how most people would choose to spend an average Saturday night. Willingly stepping into an arena to compete with another skilled athlete with an ever-present possibility that you could be knocked out in front of your friends and family isn't something that most people are capable of doing.
And that's what makes fighters both so special, and so different to most of the general populace. They are willing to risk agonising defeat, all in the pursuit of glory under the bright lights.
Basically, what I'm trying to say is, fighters have something inside them that sets them apart from most of us.
But now try to imagine the kind of person who is willing to do all that, under a much less protective ruleset and with significantly lower stakes. The kind of person who genuinely loves to fight so much that if successful, may have to compete multiple times in one night.
Though the early days of the UFC didn't have the worldwide audiences and potential for superstardom seen today, these guys still got in the cage and had no problem throwing down.