That's factually incorrect. The vast majority of voters on both sides viewed Trump's election as legitimate. [0]

There is a substantial difference between claiming that you lost for reasons that are problematic (i.e. propaganda and the structure of the electoral college) and claiming that you didn't lose at all, despite being behind by 7 million votes, because of a massive conspiracy so powerful as to make our democracy meaningless.

[0] https://news.gallup.com/poll/197441/accept-trump-legitimate-...