No John was not off his rocker.
he did not make the visions up...Jesus showed them to him. John was a passive participant. all John did was write them down.
The vision does nothing but glorify Christ . The persecuted saints needed it.
Exactly, it is the revelation of Christ, of who he really is and what he’s going to do when he returns to redeem his own and set up his Kingdom - and what he’s going to do to his enemies. Most make weird comments about the book (often calling it “Revelations”) because they don’t know the rest of the Bible or it’s author either.