Even if a large number of people ‘believe’ something, that’s not evidence of something being true. A lot of black Americans once believed or still believe that the federal government invented AIDS to kill them but there was never any evidence to back that belief up, it was just born out of a sense of persecution and victimization. It was a conspiracy theory. Similarly there’s no evidence of any electoral shenanigans as stated by the DoJ, the DHS, and any number of election officials in all the battleground states. The belief that there was just makes the most ardent Trump supporters feel better about their candidate getting fewer votes than Biden did. It’s an emotional response that the President is more than willing to manipulate to his own ends because he has no moral compass and suffers from various psychological disorders such as narcissism and grandiosity.