I get great satisfaction when I make an underwater housing and it works the way I planned. I must say I am envious of some of the latest commercially produced housings, with electronic control of just about every function. My housings only have mechanical controls. On the other hand, they never fail. I have seen the others quit occasionally.
Water coming in is the greatest risk.
I have ruined two video camcorders in recent years, both times through my error in not checking seals. I am normally very careful but it is amazing how human error creeps in. I think my age has something to do with it. I'm 67 now. I never lost a movie camera in several thousand dives in earlier years.