[Still paraphrasing Levine.] As one would expect, that didn't go well. Goldman Sachs as a company is geared to do complex low-volume, high-margin deals. Consumer banking by its very nature is high-volume, low-margin. To make things "worse", consumer finance is also very heavily regulated to discourage routinely fleecing your customers.
Which is how you get a vampire squid squad trying to feed off of a decaffeinated strawberry juice carton. Someone is going to be disappointed, and it's not the juice carton.
GS were probably willing (initially) to pay a hefty sum to get into that market, so then the question becomes: why Apple? At the time Apple had a net float of >$200B. When you have that much cash and assets to deal with, you no longer seek the help of a bank. You are a bank.
In a funny twist, their Marcus brand is still alive at least in the UK, and they are offering some of the (supposedly)[ß] best front line savings rates to attract customers. I've never seen anyone with their brand of card, though, so clearly their offered rates are not attractive enough.
ß: few other UK high street banks are offering even better rates, but every single one of them has set a ludicrously low cap on the amount they pay good rates on before dropping to just-about-tolerable rates for whatever goes above the threshold.