Even if you start counting anyone that works for a company even partially owned by a billionaire, about half of us employees work for small businesses: https://www.forbes.com/advisor/business/small-business-stati...
And it's not silly just reality.
Er ... which one?
The one where fund managers who get bonuses for quarterly performance decide stuff?
Seriously, we're getting into "banality of evil" territory ...
And what? That means it's fine to just dismiss as if it's not a problem?
But if define it that way, then "working for" becomes a phrase that has no real use. "X is working for Y" just means "Y has a lot of influence in the world" and says nothing about the relationship between X and Y. So I don't recommend using that definition.
At the time I worked for intuit, it was Brad Smith, but you could make the case we were BOTH really working for Scott Cook, who IS a billionaire
So billionaires.