The "massive swings in the middle of the night" were expected due to mail-ballots, many of which could not be counted until the morning of election day. The fact that the majority went to Biden was also expected since the Democrats were pushing mail-in ballots due to the pandemic while the president was telling his supporters to not trust mail-in ballots and instead vote in person. The fact that the votes have been counted a minimum of three times in Georgia with little change shows at least in that state the system was working.
There are minor irregularities in every election and sure, we should fix the process where it needs it. The problem with the president's argument is that he and his crack-team of lawyers have been unable to provide anything in the way of evidence that will stand up in court. If and when he can do that I will certainly listen, in the meantime it sure sounds like sour grapes and a money grab to me.