It is kind of funny that exchanges have become so successful for Bitcoin- since they lose 100% of the stuff that made BTC attractive in the first place. They’re centralised, regulated and transactions don’t even go on the blockchain. The result is that the number 1 way people get into Bitcoin is through a mechanism that has none of the attributes of Bitcoin.
What are you talking about? When you purchase coins on Coinbase, they go into a wallet that you can easily deposit to through another means or withdraw to another wallet. This is the same with Binance, Kraken, CashApp, and so on. Exceptions would be Paypal or Rob-in-'hood where they have total custody, which has advantages if the user doesn't care about actually owning the coins themselves.
Don't like the centralization of Coinbase? Then just don't use it. There's plenty of other options for purchasing bitcoins. Buying them P2P is easy as hell. Local Coin Swap and Local Bitcoins allow you to buy crypto directly from individuals with an escrow system.
By the way, not everyone is interested in the same advantages of Bitcoin. One of the reasons Bitcoin has been on he rise the last year is that it has far greater potential than a savings account to grow in value and, unlike gold or silver, doesn't take up physical space. Not everyone cares about decentralization or is averse to risk.