The question is whether and how much these policies are supported, and the popular vote is obviously relevant in this regard.
> 36% of voters said: I support every outcome of the election, no matter what
That's not really true, for all you know those voters didn't support either outcome. You would expect a "loud and clear" victory not to leave one third of people unconvinced enough to avoid voting altogether.
> but not one single person seriously opposing him and his politics
Almost four hundred lawsuits have been filed against his administration, thousands of public protest events are happening, and the tariffs themselves were just ruled illegal. What does "serious" opposition look like to you? In any case, this is certainly not what "full support" looks like.
https://www.lawfaremedia.org/projects-series/trials-of-the-t...
https://time.com/7312601/anti-trump-administration-protests-...
https://www.bbc.com/news/articles/ckgj7jxkq58o
> If the things he does were really that unpopular, he would not be able to do them.
What is the logic behind this?