In essence, the party is stupid. Both are, obviously.
And... this is exactly the problem. People together are supposed to be greater than the sum of us. But we see exactly the opposite. We discard our intelligence in favor of much simpler institutional and cultural algorithms, which fail us repeatedly. Extremely frustrating.
The reason you haven't heard of it is the reason running against your own party's encumbent President is historically a bad idea.
"Let's see if we can get a Biden sequel going in, if not, maybe we can use other existing IP, like a Kennedy. What other things are popular now? Women! Oof, Hillary in 2016, though, that underperformed at the box office..."
No, computer software, rocks, old shoes, and other things that aren’t people cannot run for the Presidency.
You don't lose your citizenship when you leave the country. You'd have to give up your American citizenship somehow, like Boris Johnson did. Hmm...he could actually move back here, become a US citizen again, 14 years later run for president, and be the first one to have lead both the UK and the US?
Edit: he just needs to have lived in the US for 14 years, not have been a citizen for 14 years. He would still probably need to re-establish his US citizenship before running (but the constitution isn't exactly clear if a natural born US citizen but not a US citizen now can run for president after living in the USA for 14 years; its unlikely to ever come up anyways).