I had a friend once who was an MMA fighter and he was a real douche. But I sense you're talking about the fighting aspect of it. I don't care. So you can throw a punch. Cool beans. I can too. It neither earns you respect from me or loses you respect.
My boyfriend wanted to get into it and did a little, which was alright. If he could do it without getting cauliflower ears, I'd give him the green light. I like to watch it, and I'd love to be able to congratulate him after a fight with all manner of prizes. But the deformed ears are nasty as hell.
I honestly like MMA fights and cage fights. But there is an exception. I would be perfectly fine with my boyfriend wanting to do this if he promises to never bring it home. I mean no fighting outside the cage. I am never be apposed to my boyfriend doing what they like/love.. I personally never stand in the way of my guys dream