Not sure about Fidelity, but as someone who owns both my own crypto and crypto shares (grayscale), here’s my reasoning —
Grayscale is in my IRA. This offers me tax advantages that keeping it in a private wallet doesn’t, and Schwab + Grayscale is more secure than hoping my computer, wallet, or sim don’t get hacked. Purchase fees are lower than on an exchange and there’s no fee to transfer it to a wallet. Grayscale + Fidelity here are both big enough that they won’t rugpull or get hacked and leave me with nothing like some of the crypto exchanges have.
I also have a private wallet with a modest crypto portfolio. This allows me to stake and allows greater liquidity and control, but the fees are preposterous and taxes will fuck me when I trade or sell.