And I know that a few collegiate officials who worked end of regular season/conference tournament games have also tested positive. So it's very likely there are college athletes who have it as well. Either they haven't been tested yet because they are relatively ok/asymptomatic (most likely), or they have been tested, but haven't made that information public due to privacy concerns.
Celebrities and those with access have been able to get tested ahead of wider spread availability.
Almost none of them would have qualified for the test under the CDC guidelines for testing, because they're all healthy younger individuals, and their symptoms wouldn't have been bad.
In the current environment, it can be really challenging to get approved for a COVID-19 test. NBA teams, however, have managed to get all of their players and support personnel tested. People like Gobert, Donovan Mitchell, and Kevin Durant would be unlikely to be known positives if they were people like you or me.
Is so much higher than what is reported.
There are approximately 450 players in the league during the regular season. Has it been confirmed that they all have been tested?
It would seem the vast majority have been.