I took martial arts, still know it, and used it. I think it's great because 1. It's a way of working out or exercising. 2. I think it's more fun than going to the gym. 3. You learn moves and techniques that will help you defeat an enemy even if you are weaker than him/her. So it can save your life. 4. You can save someone else's life.
Some yes, others I have no interest in. I'm not interested in traditional martial arts because they mostly don't work in real situations. prefer more sporty martials arts such as muay Thai, Brazilian jiu-jitsu, mma, because they're effective, but again some are ineffective for self-defence e. g. tae kwon do. I want to learn krav maga and kapap as they're based on real world self-defence, basic shit that works. I've always trained for real world effectiveness rather than for the "art". I know some will disagree with me but Indon't see the point in learning techniques that are ineffective.
Taekwondo for 2 years, but quit afterward since there wasn't much else but dancing and high flying at black belt level. The general stuff was fun though, but I could just as well learn that on my own, now that I know it.
It's fun to do, and I can also sort of call choreographers on bullshit now. :P
I've been doing Jiu Jitsu for a few months now and have done Judo when I was younger. Not very useful, but it's entertaining. Although the tiring warm ups before the actual techniques start make me hesitant to go regularly.