First-past-the-post voting incentivizes voting against the candidate you don’t want to win by voting for the candidate most likely to beat him. So scaremongering about the other candidate is a strategy often used to great effect. Trump used scaremongering against Hillary in 2016. Trump’s using scaremongering against Biden now. George H.W. Bush famously used scaremongering about crime to win.
Also their platforms are not the same. Trump has Project 2025.