The interesting thing about bitcoin exchanges is that the exchange effectively has a position in the market too, unlike traditional exchanges like the NYSE. They have to buy bitcoin from other exchanges, and if they get hacked they can lose it permanently.

Edit because I’m throttled and can’t reply anymore: the “buying from other exchanges” is really not the lynchpin of my argument. The point is that these exchanges hold inventory and are vulnerable to bank runs and theft makes them much less stable than traditional exchanges.