"Billionaire backers" refers to extremely wealthy individuals who support or invest in a particular cause, project, or person with a large amount of money. Full definition
Over # 32,000 of this money was spent on data analytics company AggregateIQ, a small Canadian outfit that has been linked to Donald Trump's billionaire backer Robert Mercer and Cambridge Analytica, who are now at the heart of an investigation by the Information Commission. (opendemocracy.net)
Parent Revolution's billionaire backers include the Gates, Broad, and Wasserman foundations. (hechingerreport.org)
A billionaire backer could help with that. (inc.com)