Update:
I’ve been thinking about what I think will happen to Trump psychologically if he looses both past behaviour (the best predictor of future behavior) and what as a psychotherapist I know about how someone reacts when their psychological defences break down suddenly, as would happen election night when his loss was confirmed.
I think he will try to deny (denial is one of the most primative defenses) and he will claim the election Was illegitimate. Then when this falls apart he will have a rage reaction.Then fuelled by his rage, this will soon turn to lashing out at his enemies. He will no longer be a rational person. It is very possible he will become clinically delusional and paranoid.
Then he will become vindictive. Since he will still be president until the new president is sworn in he will have ample time to wreck havoc on rule of law, on the Constitution, and personally on everyone he perceives as helping to bring him down.
Look to massive firings of all presidential appointees in the intelligence community. He will have Barr order investigations anyone who Trump thinks is disloyal and press for him to try to get indictments of his enemies.
This will be the period of time psychotherapists are warning about because to put it bluntly he could start an armed conflict which could leader to a major war either in the Mideast or Korean peninsula, or risky armed intervention in Venezuela.
Look for him to become more and more sadistic in dealing with migrants on the Mexican border.
In his interpretation of the Second Amendment, as he expressed in the George Stephanopoulos, he thinks that as president he has the power of a king. He will issue autocrat executive orders, some of them manifestly cruel and unconstitutional, which will end up being challenged all the way to the Supreme Court where we will see once and for all how corrupt the Republican there are.
Along the way at any juncture I’ve described, but especially as the end of his term closes in on him and he faces the possibility of criminal charges when he is a mere criminal defendant — with a Democratic Attorney General and dogged New York State prosecutors making ready indictments against him, he could easily have a complete psychotic breakdown. This will be impossible for even the most partisan Republicans from Pence and the Cabinet to McConnell on down to ignore.
We can only hope that if this happens while he is still president that the 25th Amendment is enacted.