The problem is that trump believes the president is king of America, and that a dictatorship is the best form of government. Even bigger problem: far too many Republicans seem to agree with him and will try to hasten the descent into a fascist authoritarian dictatorship. I have no idea if they will be successful, but it doesn't look like there will be much to stop them.
I think the problem is that when the Democrats are in power, they also attempt to inflate the power of the executive branch. Both parties have been doing this for a while, and are AGHAST when the opposing party gets elected. No one seems to want to take back the power the executive branch, which makes each new bad president more and more of a disaster.