This isn't even true in the US unless you're only counting profits from selling the app itself or IAPs. Android users are most likely less profitable but not by that much, otherwise I'd expect an empty Play Store.
You can start with one platform, and if successful, expand to Android (like Whatssap did). What is not realistic about that?
Maybe in the US... This works for hobbyists or single devs, but clearly isn't realistic for most companies.