One profit model that seems to be working well is selling stuff that doesn’t belong to you. Cuts your cost-of-goods-sold dramatically.
“Facebook Considered Charging for Access to User Data,” The Wall Street Journal, November 29, 2018 (online). Facebook considered charging people to access user data.
Now, I guess that’s marginally different than letting third parties see the “Facebook” user data (i.e., the data of the users of Facebook) for free, in order to develop apps or whatever. But isn’t it still the users’ information? Oh, and it might be somewhat contrary to what the CEO said to Congress about Facebook’s policy of never selling user data.