Nothing. As is the case with most social media companies, you are the product. And they do that by spying on you. Same with many other "free" services like, YouTube, email, maps, etc.
well that's make my cybersecurity lesson about spyware irrelevant in this environment, because every Free services are leeches for our information. but the justification for including spyware is where the data is going, and yet again very irrelevant.