If MicroStrategy and Grayscale use Coinbase as a custodian, and Coinbase's policy and agreement with their users is if they are 'bankrupt' client's funds/ assets become Coinbase's in order to pay off debts wouldn't that mean 2 of the biggest publicly traded companies are reliant on Coinbase's ability to not screw up?

But what is so hard about purchasing a ledger/ trezor and just adding a passphrase and custodian your own coins off exchanges?

I ask because I have a Roth IRA and would like the exposure to bitcoin there as well as in my private wallets. For all the NYKNYC people, I'm not closing my Roth Ira to buy bitcoin, and also pay taxes and fees.