A good point: “Something” was given to get all of Joe’s primary opponents to so suddenly abandon their platforms and clear the deck for Joe to walk away without exposure and without public campaigns.
As Hillary demonstrated so very well with her hundreds of millions from foreign governments to her “family charity” - AND as Joe Biden himself demonstrated by selling the Biden Brand Name for his son, brother, and their family “friends”, the patronage of a Cabinet-level position, AND the near-daily press release power of having your name in the papers and on TV by friendly press agents (er, reporters) IS MONEY.
Suddenly a message arrives to their phones... a link to a news item about the "accidentaL' or "suicide" death of one of Hitlery's or Zero's enemies... and it's "I have decided to suspend my campaign."