They relate to him. They feel put upon by the burdens of a world that left them behind. They're struggling financially while those "liberal elites" laugh at their misfortune. They grind 40 or 60 hours for a pittance that barely keeps food on the table these days. They watch TV and are bombarded by a culture that embraces sexual deviancy and vices that demonstrate the rot at the heart of their once fine upstanding country.

From their perspective, of course. Forged by propaganda and misinformation that they are too furious to examine. This idiot man-baby we see? They see a fucking savior. A man who like them knows how things ought to be. A man with the willpower and knowhow to "save America."

Where we see petulance, they see righteousness, and they sympathize. These people are furious. He's got them completely weaponized.