So how does Instagram make money? From it's userbase. Similar strategy is used in any *free* product. You are the money for them, the more the userbase, the more information they have and the better sponsors they can get for their product, simple as that. In case of Crypto Wallets, it's maybe that they can advertise a big Crypto coin without looking sus? IDK.
No it's not same as social media because while creating a wallet or using it we are not giving any personal information and also we mostly use the wallets which stores the data locally which means everything is stored on our device so wallet doesn't keep any of the information.
@OP, that's interesting question though some of the most used wallet doesn't have any ads, swap feature, or flat fee structure so they are probably not making any money.