Now, you're absolutely right that their fans and arena were awesome before they were good. I remember when they beat Dallas as an 8-seed and then the Jazz beat them. Their crowd was great. But they basically didn't have fans outside of California (and mostly the Bay Area).
In my entire life I had known exactly 1 Golden State fan up till a few years ago. Now they're everywhere. That's what being good does - it gives you bandwagon fans and broad appeal. But it is absolutely true that almost all of the fans outside that core are johnny-come-lately and they fit the annoying stereotype.