Earlier on Thursday, Rolling Stone published allegations from two current and 14 former employees, including production crew and writers, who requested anonymity out of fear of retaliation. Rolling Stone claimed they had approached an additional 80 current and former employees, but “not a single one agreed to speak on the record or had positive things to say about working on the Tonight Show”.
According to Rolling Stone’s report, multiple sources alleged Fallon had a history of “outbursts” and lashing out at staff when under pressure; that previous senior staff on the show had bullied and belittled them; and that guests’ dressing rooms were commonly known as “cry rooms”, where employees could go let out their stress.
Nine showrunners have worked on the Tonight Show since Fallon took over from Jay Leno in 2014; a much faster turnover than comparable late night shows like Late Night with Seth Meyers and The Late Show With Stephen Colbert.
I think that's a very safe assumption based on all the examples we've seen.
It’s almost like living a life where you are mostly isolated from reality, have to be isolated from the public for logistics reasons, and only have contact with people whose entire existence is to make you happy turns you into an asshole. And most celebrities are people who actively sought out that lifestyle, which means they started out with an inclination towards being an asshole.