I don't think he had any interest in public office. Way too much work and exposure for his liking.
Tom
I think that he wants the position of President without doing any of the work of it.
I get what you're saying, but I don't think it's anything like that simple.
I think:
Trump had been talking about running for high office for years, but never actually did it. He just liked to talk about it.
However, he saw other people doing so, like Hillary and Mitt, and raise their brand. Even though they lost the election. So Trump decided to do it. Throw his hat into the ring as a presidential candidate, with no plans to be president or anything. Just boost his brand, boost his name recognition, get publicity...
But a bunch of people saw him as an easy mark. Easily led by his ego. People from the ill-informed rednecks to Vladimir Putin to evangelical Christian leaders to high rolling Republicans like McConnell. People who saw Trump as a "useful idiot" flocked to the cause.
Trump was too far out of his depth to realize that he was being used. He's too egotistical and privileged to recognize that he was being manipulated by people with agendas. Agendas that weren't his own or that of responsible governance of the USA. So he kept flailing along, unable to recognize that he was sinking.
I'm sure that losing the EC, in 2020, was an unimaginable blow to his self image. He was accustomed to getting his way regardless of legalities. The realization that the Trump brand was taking a huge hit made him crazy. That's why he did what he did in December and January.
And the rest is history.
Tom