They’re both in cognitive decline. Trump thinks he ran against Obama and George W. Bush. But for whatever reason, these two men are who Americans want to run against each other.
I like Biden and think he has been a good president, but neither candidates are ideal, especially re-electing Trump
Trump's cognitive abilities are also on the decline, no one is denying that. However, he is 4 years younger and he is still noticeably sharper than Biden was around 6 years ago. Trump at the end of his second term would probably be dimmer than his current self, but still roughly on par with what Biden was in 2020/21. Biden's mental state has declined significantly that I shudder to think about how he would be by the end of his 2nd term in 2029.