With the spot bitcoin ETF, the easiest ways to add bitcoin to ones portfolio is seamlessly assured and there won't be all the need to own exchange accounts, digital wallets, private keys and bother about network transfers or the fees to pay, that may be varying at the time.
I wouldn't recommend bitcoin ETF. research about the real bitcoin and buy the real bitcoin, learn about private keys, learn how to hold it yourself in an airgapped wallet, learn about its security.
What you say is not wrong, investing in a bitcoin ETF is no different from investing in stocks, we don't actually own bitcoins or have full control over our assets. But you also need to understand that not everyone is qualified and knowledgeable enough to learn about private keys, non-custodial wallets...and we cannot deny that thanks to the emergence of bitcoin ETFs, bitcoin is gradually becoming more popular with everyone. Many people hesitate to invest in bitcoin because of concerns about its legality, their wallets being hacked...and do not invest in bitcoin. But now with the emergence of ETFs, they can invest in bitcoin without the technical barriers they were concerned about.