No.
Irrespective of political views, underestimating another person is dangerous.
I am not a Trump supporter, but I also do not consider him to be a "second Hitler".
But if someone thinks otherwise, then underestimating Trump is a mistake.
Trump can be cynical, corrupt, etc. but not necessarily stupid.
That is why when any politician says something seemingly completely stupid, I do not automatically think that this politician is stupid. Perhaps this politician is simply clever and what he said has some purpose.
There are many corrupt snakes, psychopaths, etc. in politics.
For a very large part of these people, private profit counts, nothing more.
Trump is no different, so even if he says something seemingly stupid, it may be aimed at, for example, manipulating people.
Of course, I am not saying that there are no objectively stupid people in politics.
There are certainly a lot of such people too, but I think that one should always be careful with the final assessment, because someone may be cleverer than it may seem.
This also applies to Trump.
Of course I have to add that I am an objectively stupid person, so my judgments may be wrong, but I only shared my point of view.