BlackRock would hold Bitcoin in their vault, and issue shares for people to hold in their brokerage accounts along with stonks and such.

It's important because institutions with billions to play with only fuck around with a hand full of other institutions they have a relationship with. BlackRock is the apex predator in this market for large capital.

With BlackRock offering this service, there's a place those big fuckers can go to buy paper Bitcoin.

BlackRock is legally and reputationally obligated to maintain 1:1 physical reserve for the paper Bitcoin, this drives up demand for spot as their customers buy paper.

It turns Bitcoin into no-friction collateral, since ETF shares can be borrowed against as a margin loan.

Since the entire fiat financial system runs off debt, this is a missing piece needed for the speculative attack and why the deep state has been fighting spot ETFs.

Using margin, the cost will be trivial for someone to buy 2 billion worth of Bitcoin with only 1 billion in cash.