There used to be a time when the Spurs were one of the most resented franchises in the league. That disdain didn't come from executives, either. Most personnel around the league respected what they were doing in San Antonio. Fans are something different, though. They don't have to be logical or "respect greatness." All they're expected to do is cheer for their teams relentlessly.
When your squad isn't the one winning 50 games every season and collecting championships like Infinity Stones, jealousy can rear its ugly head. It happened often during the Big 3 era, but it's been quiet on the home front for a while as the Silver and Black regained their footing.