President Biden clings to an irresponsible fantasy
Biden was replaced as the Democratic nominee because he was collapsing in the polls and it was obvious that he is in serious mental and physical decline.
President Biden believes he could have defeated President Trump. Biden is wrong, and Vice President Harris was a more electable candidate. Remember, Harris did open up a significant polling lead, had a huge amount of money in her campaign, and was effectively running as the incumbent as the sitting Vice President. Trump's campaign, suddenly faced with a completely different opponent, was sputtering for a while as they adjusted. In the summer, it did look like Harris would be the first female President.
Yes, Harris was a bad candidate who had no real policy agenda other than making abortion a national issue and having Congress "codify" Roe v. Wade in federal law. When she didn't want to answer a question, she created a word salad to try to distract from the question. People could tell she would not speak plainly, and her lack of authenticity was in contrast to Trump, who never holds back what is on his mind.
None of this means Biden would have won the election. The reason he was replaced as the Democratic nominee is because he was collapsing in the polls and it was obvious that he is in serious mental and physical decline. Trump's lead over Biden was not going to decrease. If anything, it would have increased. There is a good reason that Democrats were in a panic after the first debate.
It is fully understandable for Biden to be bitter about how he was pushed aside after he won the 2020 election. He won all of the 2024 primaries, and all of the wrangling to move him out of the way was done behind closed doors by the party establishment. Harris seemed to be seriously lacking in gratitude for Biden picking her and putting her in a position to run in the first place.
But Biden never should have ran for re-election anyway, planning to start a second term at 82 years old. Barring a miracle, Biden was not going to be physically able to serve four more years as President. It is fundamentally dishonest for someone to run for re-election when he is in failing health and knows he cannot complete his term. Just by being on the ballot, you and your political party are lying to the voters.
Harris could have helped preserve credibility for Democrats, because this Weekend at Bernie's shtick they were doing with Biden was not fooling anyone. The problem is that Harris refused to admit that Biden was in serious decline and continued to lie to the voters. Democrats could have easily made the argument that Biden is physically and mentally capable of completing his term, but that running for re-election was no longer feasible. They never made that argument. That hurt them too.
President Biden needs to get over it and move on. He is further damaging his legacy and dividing his party. He had a very successful political career, having served 6 terms in the U.S. Senate, two terms as Vice President, and one term as President. He should be satisfied with that and exit office gracefully rather than holding onto the fantasy of a second term he never could have completed.