This is where your opinion is the opposite of tens of millions of Americans.

Irrelevant. Truth does not care how many people believe it, and the last four years have shown that a large percentage of Americans will believe pretty much anything.

it's a problem when a large percentage of the population believes the government is illegitimate.

Yes, agreed, and this is actually a pretty big deal, and unfortunately right out of Foundations of Geopolitics. And there doesn't really seem to be a good solution (letting an angry mob reinstall Trump certainly is not it). As to the claims of fraud themselves, there will be a segment of the population who will always believe them no matter what, and on the other hand verifying legitimacy of these is difficult especially when multiple people have admitted to being paid to make those statements/videos. That being said, as far as I know, none of the claims would be "enough" fraud to swing the election regardless and there hasn't been any evidence of widespread fraud.