Well, it is a sad state for the country. However, if you read one of Robert Hare's books (the psychologist who developed the checklist for psychopathy) he talks about how he and other therapists are frequently fooled by psychopaths. Perhaps it takes some life experience in dealing with these people and then investigating what made them do what they have done.

People are generally not trained to, or inclined to investigate or research issues in their lives. They may see aberrant behavior and chalk it up to being a difficult person or someone who is just unkind or untrustworthy rather than recognizing the person as having a pathology. Generally, people are too self-absorbed to see beyond their own problems. But beyond this, there is the fact that people do not actually care about a person's aberrant behavior or personality as long as they are having their own selfish needs met. Thus, if voters feel that Trump is good for their bank account or he is tough on crime or he appeals to their base instincts then that's good enough, despite what harm he may do or the fact that he is a pathological liar.

Regarding your question of whether he is the "best option out of the pool" I would say that it's unwise to overlook Trump's very long list of misdeeds, wrongdoings, lies, disrespectful encounters, charges of sexual assault, criminal behavior, and so on, in favor of some selfish reason for supporting him. As we know from history, people like Trump always abuse their power.