My parents had a 120-liter aquarium before I was even born, so I've used to live with one for my whole life. When I was big enough, I started to take care of it as well.
When I grew older and moved out, I missed having an aquarium. I lived in flats too small to keep one (and the legal minimum tank size to keep fish in here is 40 liters) so I didn't have one. Finally, when I moved to a big apartment with my common-law-husband, we had enough space and money to have one. So at first I got my parents old one, and I had some black mollies and platies in it. Only after two months we desided it wasn't enough for us, so we bought a used 612-liter one with few fish it it. It's our pride and joy. We gave the mollies and platies away then because we wanted to keep big soft water fish instead.
Soon after that I wanted a smaller tank for shrimps and apple snails and I got one really cheap, and I'm loving it too.
Tomorrow I'm going to get my third aquarium, 200 liters! It's going to be our little project, we are trying to actually make it pretty. Our two former tanks are Ok, but not too pretty in our eyes, so we are trying to do something little aquascaping-like. We'll see.
Yes, we have used thousands of euros in aquariums in last 6 months, even when I'm a student with very little money, and I'm not regretting it at all!
When you love something with your full heart, you'll do everything you can to keep doing it well.
I haven't lost a single fish to a anykind of disease during my fish keeping.