Who are the two billionaires? I had thought you were talking about the recent Presidential election in the US, but Biden is nowhere near a billionaire.

Almost all of his wealth came from his salary as a Senator (1973 until he became VP) and then his salary for 8 years as VP, plus Social Security starting in 2009 and also pensions. His net worth at the end of that was under half a million.

He's boosted that to somewhere in the $10-20 million range since leaving office, mostly from book deals for him and his wife ($8 million), speaking fees (basic fee is $100k, but it has ranged from $8k to $190k), and a professorship at the University of Pennsylvania's Penn Biden Center for Diplomacy and Global Engagement ($540k).

There's an article that goes into detail [1].

[1] https://www.forbes.com/sites/michelatindera/2020/10/22/how-t...