Even if it's fueled by mania, reading tarot cards is a really cool thing to do, so i would pursue it. It'll make you an even more interesting person. I know what you mean about manic-only interests. One time i got very into religion and went to church four times in one week. Once the mania passed, so did the church-going. But i enjoyed myself and made memories to treasure when i'm depressed so i have no regrets.