Why is David Ellison a billionaire but still not on the billionaires' list?

David Ellison has become a billionaire after his company Paramount's $110-billion merger with Warner Bros. Discovery. However, he's still not on Forbes World's Billionaires list because much of David's wealth is sourced from his father, Oracle Founder Larry Ellison. Larry backed David's company Skydance's buyout of Paramount, which later bought Warner Bros. Discovery and made David a billionaire.