It is not. Nothing is hard if you are interested i.e. have fun out of it. It is about personal preferences, what you enjoy and what you don't. That's it.
E.g. for many people, literature classes or some other humanities stuff is hard.
That doesn't mesh with my personal experience. I know some very, very smart people, who have found the process itself interesting and fun, but who still find it hard and also don't think they're that good at it. Perhaps your personal experience is difference, but I've seen that interesting and fun does not preclude subjective feelings of hardness.