You are not. He is an out-of-control egotist. I suspect that the family just doesn't want to deal with his issues by creating conflict or having a confrontation. So much easier to pretend it isn' t happening.

He might even have the beginnings of dementia.

But do not doubt yourself. His behaviour would be unacceptable in most human social situations.

I bet he doesn't try this kind of thing with people whom he hasn't trained to accept his bullshit.