Your stupid scenario is to claim that winning the Primary equals winning the Election. 15% of the Electorate votes in the Primary, 50% Vote in the Election.
Even Biden Supporters have Low Enthusiasm for him, because he is a very weak Candidate. Trump OTOH has very high enthusiasm with his Base that make up 40ish% of the Electorate. A recent ABC Poll has Biden/Trump with just a 2% lead for Biden, Nationally. The only thing that Biden has going for him is Hatred of Trump, something that Democrats have, but ebbs and flows amongst Independents.
Biden needs to Inspire and Excite. He can't do it though. His Platform sucks, an appeal for Normalcy, aka, Not Trump. He has problems formulating complete sentences and meanders from thought to thought. Every so often he's aware he has drifted off, creating a cringe moment that even seasoned Reporters are left wondering what to do with.