Besides the obvious battery life and water-resistant depth, what is the functional difference between that $1400 watch and the $20 Casio I just bought for my girlfriend?
some people also like sophisticated physical mechanics (likely including GP, since he can repair watches), but i believe that's typically secondary.
If you just want something that keeps time, the $20 Casio is fine. In fact, most people I know just look at their phones. However, there's elegance and sophistication present in a luxury watch that you don't get with a simple digital watch.