A lot of hobbies are just mental
and you have to get exercise by some other means. But if you study a martial
art, not only is it mental, it's physical as well, which keeps it interesting.
People also like the whole idea that it was invented by ancient civilisations,
that there's a history to it, and there's a whole culture involved. The idea
that some old Chinese guy up in the mountains made something up, or used this on
a battlefield in ancient China, is appealing.
People do it even if they don't really care whether they ever get good at
it, or if they are ever going to be able to fight. A lot of people just enjoy
the art of it. The Chinese martial arts have a lot of nice forms, they are good
exercise, and they're more interesting than calisthenics. You could just do
jumping jacks and toe touches, but there's a whole artistry to the form, like a
dance. So, there's a lot of different reasons why people practice.