The last two years saw the rise, but not the complete fall, of “finfluencers.” With a younger generation opening financial accounts and rushing headlong into things like meme stocks and cryptocurrencies, these social-media financial influencers could temporarily create billions of dollars in market value through their recommendations, while earning tens of millions for themselves.

One of the most successful, until recently, was Kevin Paffrath, known to his 1.84 million YouTube followers as “Meet Kevin.” He morphed from being a real-estate guru to doling out general investing advice, with popular videos like “How to Retire in 7 Years Starting w/$100 [The Rule of 200].”