You act as though people didn't vote for Biden, and that everything was written in the cards by the DNC. They did vote for him, and it wasn't some conspiracy by the DNC. Biden actually stood on a stage and debated other candidates, and people still voted for him.
Would I prefer someone other than Biden be the democratic nominee? Absolutely...I didn't vote for him. But people looked at the early polls that saw him performing better against Trump. He has the highest name recognition. It isn't rocket science.
I think this election is different than 2016, fortunately for Biden. In 2016, the election was as much (if not more) about Clinton than about Trump. When you have two terrible candidates, the one who is in greater focus suffers more at the polls. Many people voted against Clinton. In this election, there will be almost nobody voting against Biden. Most are either for Trump or against him. It isn't really about Biden...at all.
Unfortunately for us, Trump will pull out all the stops to try to win this election. It's going to be a terrible, dirty campaign season, and we're all going to be worse off for it. But it makes sense, because Trump's future is contingent upon him winning this election. He is an unindicted coconspirator in the criminal case that put his former lawyer behind bars, and there are numerous other criminal and civil cases stalled in the court by virtue of his position as POTUS. Whether you believe he is guilty or not, it really doesn't matter. Those who think Trump is innocent probably don't think Manafort, Stone, et al. are guilty either, and yet they're in prison. It's no stretch to think that those who are currently investigating Trump would push forward once he lost and try to put him behind bars. He knows this. He knows that this election would also rewrite his presidency in the history books. If he doesn't win, he will go down in history as the worst president in modern history. If he does win, he might not.
As I've said before, I don't really care who is running against Trump at this point. I'll vote against Trump for the sake of the country. Whether it's Biden or someone else, it really doesn't matter. We can only hope that whoever beats Trump will be held accountable and impeached if they fail in their duties. I would be happy to have Biden impeached and/or behind bars if he deserves it...once Trump is defeated.