Trump, in his last two months in the White House, was almost like Hitler in the Berlin Bunker in January, 1945. Hitler looked like a really old man for 55, his face was lined and he had a Parkinsonian tremor. He was raving about troops that didn't exist, tanks he didn't have and battles he could not win. Albert Speer, when Hitler called for a scorched earth policy, protested that the German people could not be left destitute. Hitler, however, by that point, no longer cared about the German people. The only person he cared about was himself.
Successive legal challenges demonstrated an absence of voter fraud or malfunctioning voting machines, Trump could not accept, through his own arrogance, that he had lost. And let's not forget, he is facing potential criminal cases.
A US President can only serve a maximum of two terms and the only one to serve non-consecutive terms was Grover Cleveland.