If mastodon is fully private then how will they get money from their application? Social Media networks can only get money by ads or by selling the user's data,

If mastodon is fully private then how will they get money from their application? Social Media networks can only get money by ads or by selling the user's data, and ads could potentially track the user's data. Which companies just say NO to getting more profits, every company wants to expand so I don't see why mastodon should promise private access to content when it's really not.