If hobbies could make me rich then I would be a lot of rich, because I have a lot of hobbies. To start off this post here is a list of some of my hobbies.
Computer Software stuff
Computer Hardware stuff
I guess that is a good enough list. And actually all of there hobbies could make someone rich.
Piano could make you rich if you are good enough and you become famous for it.
Same with guitar.
Blogging can make you rich if you write really popular blogs, and you get paid for letting people advertise on your blog.
Computer gaming can make someone rich if they learn how to make good computer games.
Computer software engineering can make you rich if you develop a good program and you sell mass amounts of it.
Computer hardware engineering could make you rich if you fix/build computers independently, or for a large business like Microsoft and Apple.
Music can make you rich if you do something mentioned like about piano and guitar.
And German can make you rich if you are a great translator.
It all depends on your personal definition of rich. But you can become rich from almost anything.