When you look at the vote totals from 2016 of states like Michigan, Pennsylvania, and Wisconsin, Donald Trump beat Hillary Clinton in those states by the tiniest of margins and got less than 50% of the vote and all three states
Both candidates were extremely unpopular with the electorate. Trump learned nothing from his squeaker of a win. Democrat and Democrat leaning voters, on the other hand, learned not to take anything for granted, and made sure they got out to vote every election since
History could repeat itself. But that is a real long shot for his supporters to bank their success on.