I think it is easy to learn and set up a decentralized wallet than registering and operating a centralized account in any of these exchanges. I hope that these exchanges in the process of teaching these newbies also tell them that their privacy is compromised and they don't also own their coins.
These crypto businessmen abhor self custody and the truth, so they would rather deceive people by saying
99% of people will lose crypto stored in self custody, so people can keep their crypto in centralized exchanges and services to be used for trading and gambling by the exchange for their personal profit.
I don't know why people think these crypto businessmen like BTC, if they do, they would educate people how to use BTC the right way, and that is to move their funds into self custody after every successful trade, but how are they going to make money if they don't have billions of their customers money to gamble with.