I doubt many people really want to use them, any more than they really want to use any other megabank. A lot of people just use the bank that's closest to their house/work, thinking (and often not wrong from a retail point of view) that banks are fungible.

As a former "customer", in many cases, like ours, it's because they use their capital/position to buy loans from other businesses, and there's nothing the borrower can do about it.