I honestly think that it's more of a character and personal integrity issue, than one of either intelligence or education, because your don't need much of either to know right from wrong. Most Trumpers are not really that stupid or that uneducated, they are just lacking confidence in themselves and their ability to compete on a level playing field. Most have been raised to believe in their "white superiority" by the things their parents (often by example) and culture taught them. People need (instinctively) to feel they are not low in social statues and to many whites seeing successful African Americans and other peoples rise in social and economic statues causes envy, fear, resentment and rage. This triggers another instinctive impulse in us humans, suspicion, fear and hatred of the "other", not necessarily racism, but in most cases it drives it to extremes. During our hundreds of thousands of years of evolution from the paleolithic to the neolithic stone ages, we lived in extended family clans and close nit tribes with a long history of intercene warfare, this provided most of our evolutionary selection "pressure" as humans. Men in particular had to be able to fight and kill neighboring peoples to defend their tribes and families, the "other" did not have to be very different at all to trigger these reactions.
Tribal peoples would trade wives (women had a choice) to facilitate trade, relations and to overcome language difficulties with neighbors and the man would often live with the woman's tribe. This was how diplomacy was done and if things went "south", there was always war and the ability for people to shut down empathy for the "other" especially when acting in a group. Experiencing fear and hate triggers this evolutionary emotional baggage and activates the mental "modules" associated with these behaviours. It's more emotional than logical with Trumpers, most are simply scared stupid and wallowing in negative emotions that control them completely and turn them into hopeless suckers and fools. Being stupid often means being uneducated and with that goes a deep sense of inferiority, ignorance and confusion, this causes fear and that triggers hate. Most Trumpers lack not just the cognitive abilities required for education, but emotional skills for coping in the modern world as well.
It's impossible for a Trumper to have any personal integrity, or to be honest with others, or in may cases themselves. Their strong emotions warp and filter their perspective of reality and the alternate reality media and propaganda supports the whole sick show to such a degree that it allows them to maintain their delusions indefinitely. Nothing else can explain their blind loyalty to such an obvious turd like Trump, most would not be willing to invest their money with Trump, they aren't that stupid. Most would run someone like Trump out of their house at gunpoint or shoot them on the spot, most would not tolerate someone grabbing women by the pussy. They are willing to betray their country and their children's future, as long as the leader of their "white tribe" leads them in war against the "other", who is perceived as a bigger threat than the Russians. Many Trumpers hate and fear not just Blacks, but Latino's, Jews, Asians (Japanese internment), LBGT folks and of course immigrants. Their fanaticism surrounding guns is an expression of fear, a symbol of traditional "white empowerment" and a source of tribal identity. Just looking like a "liberal" would get the shit beat outta ya at most Trump rallies, where violence and strong emotions are always a presence.