Was there election fraud?
If by 'election fraud' you mean an organized effort to subvert the results of the election, then 'no'.
The former head of the nation's cyber-security, Christopher Krebs says 'no'.
Attorney General Bill Barr, who has never missed an opportunity to back up Trump, says 'no'.
Every governor and every state election official says 'no'.
Every local election official says 'no'.
So why does Trump claim that the answer is "yes" and why do his supporters agree? The election fraud claims are a textbook example of circular reasoning. Trump makes an unsupported claim that there was fraud. His supporters, who believe everything he says, point to Trump's claims as evidence that there was fraud. Trump cites concerns by his supporters as evidence that there was fraud. And 'round and 'round it goes.
The genesis of the belief that the election was stolen is Trump's fragile ego and his longstanding efforts to paint anything he does as an "historic" success. It's evident that while part of him thinks that he really is as great as he claims to be, another part of him works feverishly to undermine any hint that he isn't. It's not arguable that Trump enjoys a huge amount of support, even losing the election, he received the second greatest amount of votes ever, his rallies draw thousands of people, Republican voters uniformly reject primary candidates that he disapproves of. He has, in four short years, turned the Republican Party into the Donald Trump Party. It's easy to see how he could interpret this adulation and sycophancy as unassailable support making him a shoo-in for a second term. But there was part of him that knew he had to hedge his bets. Joe Biden was leading the pre-primary polls last year, and Trump correctly predicted that Biden would be his general election opponent. Trump attempted to hedge his bets by asking the president of Ukraine to open a corruption investigation into Biden and his son Hunter. In 2020 Trump resurrected his belief that the election infrastructure was rife with fraud. In 2016, when most predictions had him losing to Clinton, he made unsupported allegations that election fraud was why it looked like Clinton received 3 million more votes than he had. Leading up to the election he made repeated claims that the system was rigged against him.
Fast forward to 2020.
Due to the pandemic, many states made it easier to vote early or by mail. Trump, suspecting that people who took the pandemic seriously would be more likely to want to avoid Election Day crowds and vote by mail, began to undermine confidence in voting-by-mail (except in states or districts that were safely Republican) by making wild claims of its unreliability. His supports among elected officials made attempts to make it more difficult to vote early or by mail by going to court to prevent loosened mail-in rules, by reducing the number of early voting locations and putting up roadblocks to usage of drop boxes. Much of this was standard operating procedure for voter suppression by Republicans, with the added element of Trump tweeting about potential voter fraud every damn day. Despite all of this obstruction, a record number of people voted early, including absentee.
As the election got closer, realizing that the early voters were likely to overwhelmingly be Biden voters, and that mail-in votes in most states would be counted last, Trump began claiming that the results should be final on Election Night, despite the near-certainty that there would still be millions of votes to be counted days, or even weeks after Election Day. Even though, due to there being enough uncounted votes to make the final result impossible to call, Trump declared victory and demanding that the states stop counting votes. Entirely predictably, as the mail-in votes were counted, Biden pulled ahead in Arizona, Nevada, Pennsylvania, Wisconsin, Michigan and Georgia and retained that lead as the final votes were tabulated.. The other "swing" state, North Carolina, was won by Trump. Some states were closer than others, but Biden's lead was wide enough in all of them that a count was unlikely to change the results. Trump or his surrogates filed suits to stop counting in several of these states and in Pennsylvania to throw out virtually all mail-in votes.
I hate to use the phrase "let that sink in", but let that sink in - without any evidence that there was a problem with the election system, Trump was attempting to prevent election officials from counting votes. He and his supporters started using the phrase "count all legal votes" without a shred of evidence that any votes were illegal. Reporting the mail-in votes was described as "massive dumps of votes" when it was nothing more nefarious than reporting mail-in vote totals. Due to Republicans in many states preventing election officials from beginning to count mail-in ballots before election day, this was 100% expected. There was nothing suspicious about this.
A tactic that was in process even on Election Day itself was Republican observers agressivly challenging, in some jurisdictions, every ballot. It's true that Republicans went to court, claiming that their observers were not allowed to observe, or that they were being turned away or thrown out. In Philadelphia they were being kept 10 feet away (as were Democratic observers), Philadelphia election officials subsequently allowed them within 6 feet, which is what local statues called for. The allegation that Republican observers were not allowed to observe was not true anywhere, the few observers who were thrown out were thrown out for being disruptive and ones who were turned away either had no legal right to be there, or allowing them to enter would have exceeded the allowable number of observers. Nothing to see here.
Antrim County Michigan is one of the biggest cogs in the conspiracy theory machine. Early reporting in that reliably Republican county showed a landslide victory by Joe Biden; this got the attention of election officials who discovered, not a ballot tabulation issue by the vote counting machines, but a human error, reporting issue that was quickly corrected. A so-called forensic report by a partisan "expert" made multiple claims of problems with the Dominion voting machines. A hand-count audit verified the correctness of the machine count. Nothing to see here.
Every other claim: dead people voting, vote totals changed, mail-in votes sent in after the deadline, has been, if not debunked, has been presented without a shred of evidence. Even Trump's lawyers have said, in open court, that their lawsuits are not claiming election fraud. Judge after judge has rejected Trump's claims. Even the Supreme Court, with three of his own appointees, whom he thought would hand him the election.
In summary, there is no election fraud of any note. Trump has attempted to undermine confidence in the election, he has called for ballot counting to stop while he was ahead and to continue while he was behind, he has made farcical and ridiculous claims without any supporting evidence.
There is no election fraud.
Trump lost.