Personally, I love the wonderment and science aspect of it. I can sit in front of my tank easily for an hour a day and just watch in complete amazement of what is going on in the tank.
I love the technology aspect of it, and I must admit that I enjoyed the engineering (R&D) and construction of the system (electrical / plumbing) probably more than I enjoy what is now general maintenance of the tank. And personally, I HATE the rockwork / coral addition portion of it. That is just too artsy for this engineer. Art doesn't have a right or wrong answer, and I just worry too much about lighting, water flow, and cohabitation of differing coral species to be able to enjoy that aspect of reefkeeping (see below).
The tank certainly gives me something to mentally stimulate me when I'm not working or racing (which I haven't done this year), so that is certainly nice as well. But, I'm also a bit paranoid, not just with my tank but everything in my life (e.g. I'm always worrying at least a little bit that I'm going to lose my job due to poor performance even though my bosses have always said that I'm doing a great job). So, I always want my setup to be in tip-top shape, be it my aquarium or my race car, and quite honestly this causes me a fair amount of undue stress. So, there are times when I wonder how much less stressful my life would be if I DIDN'T have my tank.
That said, for now I just love watching all the tank inhabitants going about their daily lives. It really is quite unbelievable.
Thanks for listening Doc. You can send the bill for the counseling to my insurance company.