I believe that there is no useless hobby as long as it doesn't harm others and go against the law. For example, a hobby that person takes pictures on the street and take picture of people passing by is bad. Because it offends the other person for violating portrait rights. Expect these kinds of hobby, I think it's doesn't matter. In case of the hobby of playing oneline games may seem like a waste of time to someone, but it might be a meaningful for oneself. Because someone can build one's confidence by finshing step by step or feel healing. Of course, when limited to me, playing online games is a waste of time.