Bitcoin is a commodity, and with the amount of money they have at their disposal, I can only imagine fees aren't the only thing they're going to focus on.
I'm not sure what is meant by that word, but in addition to profit there are questions of ethics, and the enlightened self-interest of wanting a reputation for integrity, a stable financial system in which people feel its safe to participate, and a society built on merit and integrity.
Profit alone isn't a good guide to business decisions.
Their prop traders won’t be trading directly against you with the bank’s money.