The issue is the President is also the face of the country, and a lot of voters are tired of having to choose between two geriatric guys from the last generatio

The issue is the President is also the face of the country, and a lot of voters are tired of having to choose between two geriatric guys from the last generation of politics. Trump gets a huge boost from voters who are simply exhausted from being told consistently that only those over 70 need apply (especially when so many perceive that it's a generation that is selfishly leaving the world as bad as possible on their way out). Though Trump is also part of that cohort, he's not considered an insider (counterintuitively; you can't get more inside than "was a President"). So he resonates with people who want an end to business-as-usual.