Well, we have faith in the system. We've survived plenty of Democrats before Trump, and we'll survive more after.
Maybe. The problem - and probably my main objection to Trump - is his contempt for the system. Laws and systems have cracks; and often they work through conventions rather than strict rules. When tested, we often find some of these cracks and conventions are dangerous when exploited and in a worst case scenario, systems can be undermined and damaged. This really is the threat of populism: a president who breaks the law, but the system is afraid of the repercussions of punishing him for it.
It's one thing to say that he asked whether illegal things could be done and that is not per se illegal, but as a pattern of wider behaviour, Trump was a disturbing president. This includes waiving security for his family, dragging state apparatus into his attempts to dig dirt on his political opponents, overt cronyism, cack-handedly exposing intelligence for PR, firing inspectors overseeing executive function, musing about pardoning himself, directing government business to his profit-making enterprises etc. His rhetoric claiming powers he did not have can be sort of comical, except that this really is underlying authoritarianism; the way he undermined and encouraged attacks on state governors, and encouraged mobs at state and federal Capitols. This is an irony of Trump: all that fury about inattentive, unaccountable elites put in support of an inattentive member of the elite who busied himself destroying the means put in place to hold him to account. And his broad success in doing so cannot have gone unnoticed by a lot of other politicians who may be far less incompetent.
The thing is, history - including the last ten years (e.g. Poland, Hungary) shows that systems can be broken, and everyone who thinks things like "It couldn't happen here" gets proved wrong eventually. What you call "faith in the system" looks to many like complacency about or even complicity in its degradation.