That seems to happen to almost all people who are popular on social media and Youtube. They have millions of loyal followers and it really gets to their head. The same happened to Jordan Peterson. He used to have good insights on psychology but lately he seems to believe he has perfect wisdom on everything and he has tons of people who tell him that.
As far as Musk goes, for me the breaking point was the Thai cave situation where he tried (and succeeded) to suck up attention with their submarine prototype although nobody working on it knew anything about cave diving. Sheer arrogance and attention seeking.