Most wallets live on affiliate fees. Because they attract a lot of users and usage, wallets are able to squeeze in all sorts of goodies and apparently native features which are nothing more than a way to generate an affiliate commission from third-party services. They make money from methods such as directing user traffic to exchanges, integrating token swap products, etc. Hardware wallets on the other hand, have a simpler revenue model of having an actual price. There is only one problem with that model: the lifetime value of the average customer is very limited. Finally, hybrid wallet/exchanges allow you to buy crypto and charge trading fees while making money on forex conversions.