I don’t think you fully understand how narcissistic personality disorder works. If a healthy person starts getting a little too full of themselve, either because of frequent success making them feel infallible, or the Dunning-Kruger effect making them think they know more than they do, they can be brought back down by a reality check, or an embarrassing failure that inescapably shows them that they too have flaws. That’s the “shattering” or the “bubble” you’re referring to. That’s a healthy response. His mind literally doesn’t have the capacity to choose “personal failure” as an option for the cause of ANYTHING except positive results, because it isn’t even in the drop-down list. It’s super tempting to just say that it’s because he’s an asshole (he is though), but it’s a mental illness just like OCD, or schizophrenia. He could probably have masked it a little bit better when he was younger, but the clearly worsening dementia just makes it more obvious now.