The phrase "eccentric billionaire" refers to a person who is both extremely wealthy (a billionaire) and behaves or thinks in unusual or unconventional ways (eccentric). Full definition
Based on the popular Disney animated series of the same name, the original 8 - bit adventure cast players as eccentric billionaire Scrooge McDuck, who travelled around the world with his nephews, niece and clumsy pilot Launchpad McQuack, collecting treasures and defeating enemies. (cbr.com)
Rules Don't Apply, which Beatty also wrote and co-produced, is a dramedy revolving around the romantic entanglements of an ingenue actress (played by Lily Collins) and a driver (played by the new Han Solo, Alden Ehrenreich), both of whom are employed by eccentric billionaire Howard Hughes (played by Beatty). (awardswatch.com)
The man turns out to be none other than eccentric billionaire Howard Hughes, although Melvin doesn't really believe it at the time, especially when he has to lend him some money on the end of their journey together. (qwipster.net)