Not sure about a-listers. Most of them try to look young. Basically because 1) if you ask someone on the street to describe what Forever Labs is, they can't, and 2) people in general require external validation before doing something new. From what I understand, that's why everyone is crazy about influencers, macro-influencers, micro-influencers, etc. We are all trying to sell you something. Well, I am not. Aside from storing your stem cells, and the Wayfarers Roleplaying Game, and Hubski I suppose. But that's me selling my stuff. Which I think is cool. That's why I do it.why do you need influencers?
Fundamentally: Advertising with old media was understood. Advertising with new media isn't. Getting Joe Namath to sell deodorant was obvious but now nobody knows who is equivalent to Joe Namath. Thus, everyone throws money at Instagram and Zuckerberg uses it to ruin elections.