It is within the capacity of a politician to earn the trust of the voters. This trust can then be leveraged to exercise power and to execute that individual's core ideas. In Hitler we had a mish mash of populism and crummy science at work that blew up boisterously. In others we usually have a palette of long accepted maxims however ill founded.
Electability remains the key element. Trump in particular turned out to be electable. His ideas are actually quite normal and he is hesitant to adopt extreme's although he revels in surrounding himself with extremists the more to frighten his opponents.
Today most who rise to positions of power are broadly educated and normally skeptical. Trump is no different. Even if he depends of media there is enough debate to sharpen opinions. That is the society we now live in.
Long gone is the log cabin and the weekly trek to the church and general store for news..