Because people practice it "for fun", that's why. Or to have something they can do with their kids, friends, or significant others. Or to pretend they're some ancient warrior. Or to seek to achieve "moving zen". Or to deeper immerse themselves in a culture that's not their own. Or to have an outlet for their emotions. People enter martial arts for any number of reasons- why pass judgement on their motivation?

Personally, when I practice, I do so with an eye towards efficacy, but at the end of the day, I don't live in a dangerous area, I don't have a profession that requires me to know hand-to-hand combat, so if it wasn't fun, I would have stopped years ago.

Edit: "Martial Arts was intended for combat be it war or self-defense."

Or sport/tests of "manliness". Oldest evidence of unarmed combat training is wrestling in the Beni Hasan tombs in Egypt. Other cultures (Greek, Indian, Chinese, Central Asian, Mezo-American, etc) also practiced forms of wrestling, often for sport/entertainment, though the skills were seen as essential training for soldiers as well. Just some historical input.

Not to bash any other sports but martial arts are certainly as "effective" as football, ballet, basketball, etc. You do it to become skilled and to understand what's involved in the martial art.

As for martial arts not being an actual sport--of course it is/they are. There are thousands of tournaments around the country (and world) in all sorts of martial arts. Some people practice martial arts to be effective (successful) in tournaments.

But even though--and I guess this is your point--most martial arts as they're taught today aren't intended primarily for war or combat, the skills that they teach have a lot of practical value. I'm not going to get into the whole silly argument of "street fighting skills" versus martial arts. But the techniques that are taught will certain give someone a significant advantage over someone who doesn't have those skills.

The initial reason for many people that begin martial arts is self defense. However, as they progress, me included, they realize that martial arts is not only about slef defense. I still practice martial arts because I enjoy it. It's a big part of my life. Of course, I do look at what I learn and see how and why it works; I don't just go blindly taking classes because I enjoy it. I take time to figure out how the stuff that I learn can be applied and I learn from the material. But I continue to do all of this becuase I find it enjoyable. I don't just practice it "for fun," there's more than that. I practice it because it's my life.

I care a lot. Quite frankly, that's why I quit judo and started Greco-Roman wrestling. I loved Judo and I admit that it is very effective, however, I disagreed with many of its elements. I love greco-roman. When we practiced Judo, what I hated the most was how dependent judokas are on the gi. If I'm getting in a fight man, I'm not grabbing someone's shirt and no one wears a gi. Also, judo is called the gentle way, but quite frankly it is very dangerous. In wrestling you can defeat someone and control whether or not you want to hurt them. It is not dependent on the gi or any other substitute, it is completely artistic. Ever since I started I have become far more physically stronger. Everything from my calves to my shoulders have increased in strength. The ligaments have become tougher and I can feel a huge difference. It's amazing and excels the wrestlers strength, speed, technique, and mental prowess as well.

I enjoy studying and learning martial arts. But I practice it for self defense and for the knowledge. But everyone has their own reasons for practicing. Some just for sport, exercise, fitness, fun, because other friends, or relatives do it. Some even hoping to lose weight.

Edit:

One guy mentioned that he quit judo for greco wrestling. I hope he is satisfied in his chosen form of training. That matters a lot. However, I must add that judo is not as dependent on the gi as stated. That is a very elementary way of looking at judo. I remember a fight I got into after I began training in judo. The fight should have been avoided. But I was immature and continued to argue with this guy. I wasn't thinking about fighting. But they guy came after me and tried to hit or grab me. I don't know. The next thing he knew I sent him flying with what I was taught in judo. He wasn't wearing a gi. I didn't use his shirt although I could have. I used what he gave. His arm cam forward to hit or grab and that is what I threw him with. There was another fight I got into that should have been avoided. A guy and I was were talking about each other. I thought we were just joaning or playing the dozens. I was in crutches from breaking my toe in judo. He said something about me not being able to do that karate stuff right now while I was on crutches. I didn't take that as a challenge. I was still telling him how soft he was. Next thing I knew he grabbed me and shoved me into the lockers. I knew I couldn't fight him standing up on crutches and he should have put his hands on me. So I threw him on the floor in the locker room, dropped my crutches and began to choke him and banged his head on the floor. I might have killed him as I snapped. But some other students pulled me off of him. I was about 4'11 and weight about 95lbs. He was about 6'1. When they pulled me off my legs were in the air but I still had a hold of his throat and dragged him until I could no longer hold the grip because of his weight. A friend of mine i high school that trained with me saw a man beating up his gf in a parking lot. He came to her defense. The guy took a swing at him. He threw the guy through the windshield of his own corvette. The guy sued him, but later dropped the charges because his gf said if he didn't she would charge him with assault.

I do, I had to. I initially enrolled my son because he had trouble in school and the discipline helped him to do a lot better. But for myself I got into it because my life was not safe, I had kids to take care of and I did not want to carry a gun. Now my life is a lot quieter, the kids are grown but I still continue my martial arts training "for fun" but just to be on the safe side I still care a lot about what I learn and pick my teachers carefully, just in case.....

I enjoy the time I spend with people in the dojo. I enjoy the workout, and I enjoy learning so that's all of the "fun" for me.

But I also enjoy learning how to apply what I learn and being able to use it if needed.

To me martial arts is part of my lifestyle, going to class, teaching classes, and practicing are just part of me.

Martial artists do it for self-defense. It's just that the idea sounds psychotic and paranoid to non-martial artists (yes, it does.). So the martial artists say it's for fun, so non-martial artists don't see them as psychos.

maybe because i find the martial arts that i do fun and i want to do them. the same reason someone would want to do football ballet ect. pretty dumb question mate.

To anyone that practices MA "for fun", do you consider whether or not what you're doing is effective? Do you look at the training and ask yourself how realistic are these techniques? Why practice a Martial Art "for fun"? Why not play football, ballet, baseball, basketball, etc an actual sport, instead of do something like MA?