Well if you consider all billionaires and not just the top of the top, the trend is the opposite. Billionaires who inherited their wealth were 55.3% in 1996, 41.9% in 2001, and 30.4% in 2014.<p><a href="https://piie.com/publications/wp/wp16-1.pdf" rel="nofollow">https://piie.com/publications/wp/wp16-1.pdf</a>