We have seen mass psychosis, for example, in the death of Princess Diana and we have seen election psychosis at the time of the emergence of Barack Obama but the Trump phenomenon is unique.
As you point out, he has few redeeming human qualities apart from the ability to make money with other people's money, including the taxpayers, but his character failings are accepted as virtues and even aped by his supporters. We see this time after time in this forum when they swarm.
The grave danger is that the psychosis will carry him through the nomination but the general public will not be seduced and he will be utterly repudiated at the polls. His unfavorable ratings suggest that the anxieties and frustrations which energize conservative voters are not as relevant to Democrat and independent voters who will be immune to the psychosis.
Do not discount the effect that 30 years of a debased popular culture has had on the American psyche. It is not only liberals and moderates who pump up the ratings of the garbage that is out there. A large number of people who self identify as conservatives make up the loyal audience of a Howard Stern for example. Since the population today is less cultured and literate than the it was in 1955 and before, here we are with a debased candidate for a debased electorate.