It is obvious to many people. Iowa was obvious to many people. Iowa had to change their vote totals after the outrage. Exit polling was the most accurate polling until recently. The results are in and the errors keep happening in one direction.
Your Biden voters acting coy about their vote with the exit pollsters is absurd.
People in the DNC and Clinton campaigns conspiratorial illiberal and illegal behavior was exposed. The Podesta emails were published though liberals were loath to talk about it at the time. They, instead, spent 3 years hyperventilating about Russian meddling without saying a word about what those hacked emails revealed.