It's perfectly fine. People have all sorts of obsessions and intense interests that range across a variety of subjects.
I find motorbikes and sports/supercars very interesting, although I would never get behind the wheel of one.
I've love trains since I was little - watching Thomas the tank engine and just getting loads of the merchandise. As I got a bit older, I always wanted to get some of the Hornby train sets but had to settle with Scalextric/Slot Car Racing because my parents believe I would just get bored of watching a train go around in circles on a track and because there wasn't enough room in the house. Nowadays, I still don't have any Hornby/ electric train sets but I got around it by having a railway simulator on my computer.