Activation lock on newer Apple devices is pretty bulletproof. Unless you’re stealing it for parts, it’s not gonna be worth your time and since the repairability is pretty low, I don’t see theft as being a huge problem for the Apple Watch.

Personally I would be more worried about it falling off with magnets. I was in a river this weekend and wasn’t worried at all, but if all I had was magnets holding it on, I would definitely think twice about going in with that setup.