How?

There's small-scale fraud in every election on both sides from people mailing in their dead mom's vote or similar. It's a felony and I don't see how tens of thousands of voters in every state could get away with it.

I personally think stuffing the ballot box is too resource intensive, aside from all the measures taken to prevent it. 100k votes, each taking 1 minute to fraud, would be 1666 man-hours, and I bet it'd take a lot more than 1 minute per vote. Suppressing voters is way easier and effectively the same as stuffing the ballot box.

Although I'm sure it'll be thoroughly investigated, It's his right to sue and press for recounts and investigations. That's not even unprecedented. I just don't see how a fraud campaign across so many states could be possible.