2. who are "they"? and why do "they" care what you do at your own time?
Please explain farther.
Everyone is different, you obviously don't like martial arts. People in the martial art section enjoy doing martial arts. There is a plus side to having martial arts as a hobby; so you can defend yourself to some degree. And yes, if people gang up on you even with martial arts it is very hard to defend yourself. I don't quite understand your second question, who is "they"?
Fine then, stay at home and stay in front of that computer screen and be a coward for the rest of your life. No one forces you to do it anyways.
Well in this case, just stay inside your house if your so afraid that nothing you do will help you in life.
Then dont do it, simple
Why the hell should you get a black belt if.
1. People always gang up on you more than five on one.
2. Why should you even do martial arts if they want to blame all the things they do on their own time on you.
Why the hell should I get a black belt.?