"His success at that persuaded him that he was an Important Moral Authority."
Isn't this rather common in artists? Bono of U2 comes to mind as a very pronounced example.
The problem with being a well-known artist is that you have way too many sycophants. Imagine getting dozens of ChatGPT-like fawning messages every day, but from real people, and not just over e-mail, but whenever you stray out of your house and someone recognizes you.
That will mess with self-image of almost everyone except the most stoic personalities.
Adams was a mediocre bureaucrat who discovered he could make a living as a competent comedian. His success at that persuaded him that he was an Important Moral Authority.
He started as a banker and ended as a self-harming prosperity preacher - not exactly a rare archetype in the US.
The funny parts were funny. The rest, not so much.