I think what makes them interesting to a lot of people is 1. they dominated the world back then and 2. there’s a lot of room for imagination because we know comparatively little about them. How they lived, how exactly they evolved, what they looked like, sounded like. It’s anyone’s guess and some consider that kind of guessing fun. The lack of definitive answers also means there’s always a chance of groundbreaking new discoveries. A fossil with intact pigments for example is to the paleontologist scene what getting ones rocks off while high on crack is to the layman. And then 3. the Jurassic Park franchise got a lot of people hooked.