Are good photographers obsessive

Yes and no. There must be some who aren't but the attention to fine detail and perfectionism required of professional photgraphers means the photographers naturally obsess.

I've spend a long time thinking about the value of an f2.8 lens. The value is beyond the premium except when getting the shot is a priority. Sports photographers spend several thousands on digital SLRs which meet this need and if they're not good enough they change brand. Sometime the perfect light and moment appear briefly and if the camera or the photographer are too slow the moment's missed.

There are little things about the equipment which might not make sense to average users. Another thing I'm thinking about is high sync flash. What this means is an external flash can be used at any shutter speed. In practice this means flash can be used in daylight to soften shadows. Really that's the only purpose - total creative freedom no matter what the situation. The problem is it's a small difference in apparent and real value for some forms of photography. Live music photographers rarely use flash.