We watched 20 Trump rallies. His racist, anti-immigrant messaging is getting darker.

To be perfectly blunt and without the typical humor that's been associated with him... I would say it could be a fear he sees of him losing ground with the realization that all of his problems and misdeeds are finally catching up to him and one of the very few paths out is slipping away.

For someone who could be seemingly suffering from what may be, or something similar to NPD; seeing a lot of what one created, appearing at least to their eyes, to be starting to erode can be very distressing to one's psyche. This I imagine would cause that person to lash out, similar to how one would act in a fight or flight scenario.