On the one hand, a single person’s ability to change government policy is pretty small. You can vote, call your member of Congress, or sign a petition. But it’s only true in a limited sense that the rules change if you ask.
On the other hand, a corporation’s “purpose” is to do what its owners ask it to do, not necessarily to maximize profit. (See Dodge v. Ford and its interpretation for caveats and nuances.) If Facebook’s shareholders vote for it to convert all its assets to glitter and distribute it evenly over the surface of the moon, that becomes its “purpose”. That won’t happen, just like it won’t happen that the people of the US vote for the US to do that, but in principle it could.
Facebook trades partly on its reputation. It has an incentive to not openly harm society and its members, because that would be bad PR and thus hurt its long-term profits.
Corporations and governments are different in important ways, and frankly I often wish they were more different, but I think it’s fair to compare them in this context.
Au contraire, corporations are more likely to change at the behest of the public than are governments. This isn't surprising, because they have more to fear. A decrease in sales due to bad publicity is a very real possibility, whereas a large-scale armed revolt by the citizenry is not.
One is a corporation whose purpose is to extract value in any means possible - even were it to the detriment of society and its members.