Facebook is primarily a propaganda organization. It's main objective is to influence, manipulate and subvert the user's judgment and convince them to buy something --- be it physical product or ideology. To further this objective, it has developed an incredibly detailed psychological profile of each individual user using deeply personal info willing surrendered by the user themselves. It's skill at doing this is what…
The claim in this comment is that Facebook's business is to sell ads, but facebook users actually the thing being sold, rather than the customers. This has caused Facebook to become evil and do evil things.
However, if you think about it, almost any social "product" follows the same pattern.
Consider Bars and Clubs. On the surface it seems like their only purpose is to sell alcohol to the patrons, and in a way the patrons are just a way to make the club look more popular to attract more alcohol consumers. But most bars don't become propaganda organizations delivering ethanol via an IV drip. Bars want to create a fun environment that is sustainable in the long term, so they avoid strategies that are likely to harm their customers and prevent them from coming back. Some bars are undoubtedly evil, but it's usually pretty obvious and there are regulations to detect and limit misleading or dangerous behavior (spiking drinks, racial discrimination on entry).
For a lot of people, Instagram is more like a Bar than a physical product. It's a place you go to interact with people and have fun or catch up. Facebook wants people to enjoy themselves and keep coming back. Sometimes people have a bad time or are harmed, but it's in Facebook's best interest to understand that and change things to make Instagram safer and more enjoyable, so people will keep coming back and "buying drinks".