Decent people lead Google, Facebook, and the other giants. They are very smart and hard-working. They are no more greedy than anyone else. However, corporate leaders in America put shareholders first. That does not always serve users and the public interest.
Seven trillion dollars of corporate power is unprecedented in my lifetime. These five companies are worth over three times as much as the top twenty-eight telcos across the world (below.) I believe each is now spending over $100 million/year for influence.
Consider a thought experiment. Would the world be better off if the giants were broken into smaller parts, say worth up to $500 billion?
Capitalism works best with strong competition. If Instagram, Whatsapp, and Facebook how to contend with each other, they would be more innovative. One might even offer a service that didn't abuse your privacy.