I just love sports, so I would watch team USA in the WC, but that's the only time I could muster any care for soccer until I actually started going to MLS games. I started going to RSL games when they were still playing in the Utes football field. It was a terrible stadium experience. They'd have 12-16k people there and it just felt so empty. But I liked the games OK.
In year 3 of me going to games occasionally, they built an awesome new 22k stadium that they were selling out and made the playoffs. When the stadium is the right size for the crowd, the crowd makes it awesome. I got to sit in a box right on the goal line on the side of the field where we scored a game-winner in the 93rd minute of the franchise's first playoff appearance. When you experience something like that, you're in forever.