What about the less constitutionally troublesome choice of simply tossing the constitution aside and declaring himself president for life? As I recall, he had a trial run at that a little over 4 years ago. Seemed to be a decent proof of concept to me.

He didn't do that four years ago. Back then, he was also trying to travel under a hack or kludge, trying to claim that he was the rightful holder of the office without just tossing the constitution aside.

It's the timid approach. You're trying to stay in office - but using a method that if you fail, you're not up against a firing squad or in jail the rest of his life. Trump almost certainly thought that as long as he was using lawyers to stay in power, there was no downside. Try to stay President - but if you fail, no harm no foul and you just get to be a rich ex-President. TPTB disagreed that he personally had stayed on the correct side of the line between legally creative challenge vs. criminal conspiracy, but he was definitely putting in the effort to position himself on the correct side.

Tossing out the Constitution altogether? You better be damn certain that you'll win, or else you're up against the wall.