You're not investing in bitcoin yet, because this are exchange traded funds you're investing on and they are stocks and shares in which their primary aim is to use bitcoin price to determine for their market standards and price as well as the productivity yield upon each investment to either be for gain or lose base on the bitcoin price.
Invest or don't invest, it is not important. The more important thing is you don't own any bitcoin or fraction of bitcoin by buying Bitcoin ETF shares.
You can consider yourself as whoever, it's not important, but if you actually own bitcoin (by owning Bitcoin private key), you are good and only need to do remaining steps rightly like how to backup your wallet, and recover it with backups.
You can not trust any company, anyone to keep Bitcoin private keys and stores bitcoins for you. You must do it by yourself, be your self custodian, and have your own bitcoin bank.