Madonna sang the praises of nonfungible tokens, or NFTs, depicting cartoon portraits of bored apes.
Tampa Bay Buccaneers quarterback Tom Brady appeared in commercials endorsing crypto exchange FTX, which collapsed suddenly in November.
And Kim Kardashian gushed about EMAX tokens on Instagram.
Now they and other celebrities are facing civil lawsuits from investors who suffered losses on virtual assets, as well as scrutiny by regulators for allegedly duping the investing public.
The legal actions, which have prompted some agents to caution their clients against financial endorsements, could clarify the ground rules for crypto promotions, as well as the hurdles investors must clear to hold promoters liable when investments go south.