Okay, Mike, you have perfectly described the what of them and us, good and bad, so let me take a stab at the why.
The human defense mechanism is quite primitive. It is the tribal impulse of them and us springing from the base ego. Thus the more primitive the personality the more black and white (Trumpian) their outlook.
Alas, this is well aligned with the unwritten, the universal law of probability balance. This law says that at some point in time all creation and good must be offset by destruction and bad — stars are born, stars die, peace is offset by war, love by hate and Obama by Trump — balance.
In a way the founding fathers’s experiment in democracy was an attempt to rise above this primitive them or us impulse, this universal law of balance. But it has been and will always be an uphill climb against nature’s universal law of balance and man’s primitive defense mechanism, the simple them and us impulse that Trump and other would-be tyrants are always pushing for personal advantage.