Very often famous persons promote meme coins. That is why they raise in price so much more than other coins. And such big growth attract a lot of intention to meme coins.
Famous persons promote meme coins because they get a lot of money for promotion.
Now promotion of different coins is in demand and costs a lot of money.
I don't think Elon promotes though for the sake of money, he's a troll and always have been, so I don't think all famous persons are paid to promote but just promote themselves as they know that Bitcoin has become a big community, although it is true that some celebrities are paid to promote some coin alongside with big exchanges promoting altcoins that paid them to, but promotion alone is not enough for a coin to succeed of course.