And your point is extreme, for example. You are claiming that he is unfit. That's your opinion but wasn't the opinion of millions of people.
Personally I think he is extremely unqualified, and should not have been elected. Again, this doesn't matter.
The point is, he is the president, trying to delegitimize him serves no good to this country.
A democracy is built on the losing side acquiescing and letting the majority rule. This is why it was a big deal when Trump stated ahead of the elections that he would dispute them if he lost: it was a threat to the Democratic process. A civil war is the final result of this, when the minority does not want to give up control.