Don't worry about the bike ending up like the rollerblades. Sometimes you have to go through a few different activities before you latch on to one that you like enough to continue with.

Even biking, per se, isn't all that important. If one can find an activity, any activity, that they enjoy, that gets them outdoors and moving around, that results in exercise and resulting good fitness, then that's a wonderful thing. Biking is but one of many choices. (And biking, of course, also has a very practical & utilitarian aspect as well, which can be exploited for fitness).