Exotic Pets

I’m never going to have an exotic pet. The closest I’ll ever get might be a reptile of some sort. But here’s the thing, of all the exotic pets out there, I’ve never heard of anyone having the one I would want most- a sea otter.
They’re cute, playful, and intelligent. Is the cost of a sea water tank that daunting? I mean, people have lions, tigers, chimps, and even bears as pets. I just find it odd that I’ve never heard of someone having one of these cute little guys.