If an interest makes you happy, then why does it matter if it's "useless"? Many people are fans of TV shows and movies and other "useless" things but no one trolls them for that.
Even so, I am not a Pokemon fan. My interests include drawing and creating my own cartoons, writing stories and making crafts. They are not just interests but special talents that I have. I've used them to make gifts, make my house more enjoyable to live in, and even earn money.
Of course, if they make *me* happy, that's what matters more than anything else in the world. Looks like the OP has no real knowledge of that. 