Well you'd think that but no, it doesn't make it necessarily so. Many MMA people I know are also doormen, police officers and others who face 'proper' violence many times yet they can easily switch from what they do in MMA and what they have to do 'outside' I've done it myself. It's actually easier than you think.
Training is different from fighting, you don't have a ref when you're training lol. Too many people assume you can't switch form competition rules to no rules, I suppose for those who don't face violence everyday it may be harder but for those that do it's much easier.