brain-addled? I think he has been so dishonestly self-aggrandizing for so long that now that he is riddled with dementia, he often really doesn’t know what is true anymore.
He no longer has much of a “filter,” and just blurts out things that are self-aggrandizing because THAT is who he foundationally is. So even though we know very well that these things are not actually true, he keeps saying them because they give him comfort and an ongoing sense of self in light of the dementia (which can rob him of his sense of self).