People take advice from those whom they consider to be "in the know". For most people, they don't know anyone in the cryptoworld. They also don't know who the main "celebrities" are of the crypto world. So, they have to go to someone they "know" talking about something that they don't know.

When JP Morgan wanted a stock to go up, he would just say something like "GM seems very undervalued." Because he was a banker, they considered him "in the know", even thought his knowledge of the car business was no more than backing DuPont purchasing GM. A modern day version is Jim Cramer. "Buy, buy, buy!!" or "Sell, sell, sell". Jim Cramer doesn't know about all of these stocks, especially the ones he is asked about on the phone. He is just taking a guess and because he's a personality in the stock trading world, people buy or sell based on what he says. He got into trouble for this and now puts a weak disclaimer out before his show. It doesn't change the fact that what he says might influence the price of a stock.

So, Musk and Trump are business men. Very successful business men. It isn't unusual for people to follow what they say.

Bill Gates is a successful salesman. He was never a great programmer and he's not a virologists. Yet, people are listening to what he says about health and medicine.

People, in general, are too lazy to research information on their own.