...
First, the easiest person to fool is yourself. I do my best not to discern fact from fiction based on how I feel about it, I want information I can evaluate and weigh. I'm aware that the signal to noise ratio here is so poor that we are unlikely actually be able to get this kind of information...
From where the average American sits there is plenty of reasons to believe the election was stolen while others see the same events unfold and believe the election was legitimate.
Are you going to believe Joe Biden? The Democrats? The mainstream media?
Are you going to believe Donald Trump? The Republicans? The alternative media sources?
Are you going to believe our self appointed voices of "reason" here?
Are you going to believe our purveyors of outside of the box theories here?
All cases have narratives, a story, made with circumstantial evidence buttressed by facts.
If your operating assumption is our elections have pretty much been legitimate all along you will construct a story based upon that foundation.
If your operating assumption is that elections can be rigged and have been rigged through fraud and other means throughout history then you will construct a story on that foundation.
Complicating matters is it might be easier to survive "believing" the false narrative, the lie, or not rocking the boat, as that way you can blend in with the crowd and not become a target. Live a comfortable life. It might also be easier than the horror of acknowledging just how corrupt and lost of a culture we're living in currently.
While I believe there was manipulation and probably this and many elections were "stolen". That's just based on my interpretation of the circumstantial evidence, obvious fraud and overall distrust of the system, media et al.
I also believe that extraordinary claims require extraordinary proof, ie like I said earlier "The case needs to be obviously true, incontrovertible in facts and overwhelming in evidence."