I started saltwater with a 55 gallon reef, and before that hundreds (yes, hundreds) of fresh water tanks, so I have been there. I guess it's like gardening, if you get okay at it, you want a bigger one...
As a kid I grew up in hospital waiting rooms. There wasn't any good television in those days (I didn't think so anyways) and almost all hospitals had a fish tank in the pediatric wards for kids like me that needed to think about something else besides pain and fear. That's where it all started over 50 years ago.
I still zen out on the fish tank and while I don't deal with as much pain as I did when I was a kid, I still find myself using it to relax. MUCH cheaper than a shrink and it works. So, bigger must be better, right?