This sort of shows which side of the political divide has been living in a bubble, or at least which side has been living deeper in a bubble, for the last four years.
Biden winning shouldn't have even been surprising to anyone who has been paying attention. Even if you thought Trump would win, the possibility of Biden winning was real. The fact that a lot of people cannot even conceive of Biden winning without fraud shows that, not only have they not been paying attention, they haven't even been living in reality.
Trump won four years ago by the slimmest of margins in 3 key states, even if the EV vote wasn't all that close. And Hillary, a flawed candidate, still got 3 million more votes than Trump. Over 4 years, Trump never hit 50% approval in any poll, even in the early days of a national crisis when there's a tendency to rally around the President (and before his incompetence was fully revealed). And in the months leading up the election, Biden was consistently and steadily ahead of Trump.
So there were plenty of signs that Biden would, or at least could, win this election. Not recognizing that to the point that you feel the Biden win could only be the result of fraud is delusion on a massive level.
It's sometimes hard to be objective about yourself, your feelings and your opinions. We all feel that we are right, and our opinions are the right opinions. There's a tendency to think that, since we are the most reasonable and our opinions are the right opinions, most people will agree with us. But this election showed that one side is clearly in the minority, with opinions that are out of step with those of most Americans. That may be a hard thing for people to accept about themselves.