Once upon a time to purchase Bitcoin was not very easy back then.
It's because in the past, the Bitcoin adoption was very small, and there were very little people who are sellers and buyers. It was like big barrier to find sellers and buyers for a Bitcoin trade but fortunately the Bitcoin pizza trade changed many things for Bitcoin adoption.
Pizzas for bitcoins?Did Laszlo Hanyecz exchange 40000 BTC for 8 pizzas, not 10000 BTC for 2 pizzas?1.The idea of buying versus owning Bitcoin is not the same thing as before.
It's the same with people who buy bitcoin and store bitcoin in their non custodial wallet, nothing changed, nothing prevented them doing that if they want to be their self custodians.
2: Convenience Is Replacing Self Custody.
It's people change, not Bitcoin change. When people understand risk of online sites, centralized exchanges, custodial wallets, they will decide storing their bitcoins in self-custodial wallets.
3. More Bitcoin Users, Fewer Bitcoin Owners?
Don't care about it, pay attention on your bitcoin accumulation, storage and security.