It has always been easy to buy BTC, if you don't care about your privacy, you can buy it in a centralized exchange, but if you do care, then there are enough decentralized exchanges to buy BTC, as for storing it, open source self custody wallets like Electrum, Sparrow and BlueWallet is great to use. I think even institutional investors should learn the right way to buy and store BTC, because not their keys, is not their coins.
Self custody is a thing that's valuable for people that are tech savvy and organized enough to keep their privatekeys safe, that i agree with.
But i am not sure how much more privacy dex has over cex. I mean you have to buy the original crypto you are using to trade it to btc in the first place. And at least in EU, you need to reveal your id at some point for that. Even btc atms are using kyc these days, or when you are using bank card to buy it. Only semi-private way is to buy with cash from some random person p2p. And even then you could end up in trouble at some point when you need to cash out, and you don't have the proof of origin of that btc to provide.