What played the biggest role in Trump's win?

[ProgressiveModerate]

There's cases to be made for all 3.

For Biden-->Trump voters, the case is just how universally most of the Country swung towards him, and some specific communities where it's very clear there were a sizeable number of vote flippers.

No-vote-->Trump voters can be seen by how Trump got higher raw vote totals than 2020 in many parts of the Country, including in cases where it can't just be explained by growth.

Biden-->No vote because there's a decent amount of evidence that Dem turnout was disproportionately down in most cases.

[Meclazine for Israel]

I watched an interview the other day that said the "incumbent losing the election" is the primary cause.

It's hard to say.

I think Trump was, politically, too powerful a figure and the Democrats appeared weak and broken, particularly following Biden's debate performance.

Trump Extends an Olive Branch to Democrats

https://www.instagram.com/reel/DCVTLNwNHXV/

[jaichind]

Biden-->No-vote voters   

Still given the turnout surge of 2020 and the likely reversion to the mean Trump should get a lot of credit for managing to turn out a lot of his 2020 low propensity voters to come out to vote for him again.

[Zenobiyl]

Depends on how you interpret the title question.

In terms of Trump actually winning, it was definitely Biden → Trump voters. But the extent of Trump’s win was due to Biden → No-show voters. You can see this in the collapsed turnout of states like Florida, Texas, New York, etc

[Pericles]

Harris gained voters or equalled Biden in the swing states, so the election isn't really a story of low Democratic turnout. However the uniformity of the swings means massively differential turnout is unlikely. So we'd have to use Biden-Trump voters to explain how the Blue Wall flipped, which ultimately is the election that matters despite all the drama in the other 47 states.