In one scenario, Trump loses but his supporters are able to nurse a permanent grievance that the system wouldn't even let their guy compete. Not for the abstruse reasons that Trump's team tried to conjure up after the 2020 results came in, but because of something that's easy to understand and easy to see as a legitimate grievance.
In another scenario, Trump wins the Electoral College—remember, these states weren't likely to vote for him anyway—but with a far lower percentage of the popular vote. Indeed, the popular and electoral votes would be even more mismatched than in 2000 or 2016. In terms of democratic legitimacy, that outcome might be even worse for the future of the country.