The entire point of Bitcoin is to eliminate counter-party risk with respect to money. Paying extra for counter-party risk is just asking to lose all the money you poured into those accounts.

If Fidelity really wanted to embrace Bitcoin, their service would consist of teaching their customers how to do self-custody properly. But teaching old people how Bitcoin works is hard; it's so much easier to leave people ignorant and tell them that custodial Bitcoin is the same as self-custody Bitcoin.

Plus, when Fidelity loses tons of money along with the rest of the financial system, all the Bitcoin they purchased (assuming Fidelity isn't using a custodial service) will get sold at auction -- to be bought by Bitcoin maxis.