Power does not corrupt. It reveals. If you have the power to do whatever you want, it becomes apparent what you wanted to do. If having this power makes you do evil deeds, it means you already wanted to do evil deeds but lacked the power to.
You can’t say “no politics intended” and then directly discuss politics. The answer will invariably include politics.
Trump didn’t want to be a politician. He wanted to be president. Being a senator or congressman is a job, but being president is a mark of prestige. If he can become president again, he will, because it makes him look good. There’s no point for him in taking a lower position with less power.
There’s an episode of the Good Place where they discuss this exact thing (well, replace “immoral” with “romantic”, but still), and I’m pretty sure the motivations are the same. They don’t actually believe in determinism as much as they claim, but they don’t want to be responsible for their actions and determinism is a good excuse they can use. You can’t use logic to get them out of this belief, because it wasn’t logic that made them believe it to begin with.