Tristan Harris gave a compelling talk a couple of years ago that dug into this question without assigning moral blame on us. [0] He's identified several principles, probably familiar to most of us and seemingly innocent, that he says have led us to where we are now:
* Give users what they 'want'
* Disrupt everything
* Technology is neutral
* Who are we to choose what our userbase does with our platform?
* Value growth at all costs
* Design our interfaces to convert users
* Obsess over metrics
Tristan is part of the Center for Humane Technology, a nonprofit that, in my opinion, deserves more of our attention.
[0]: https://www.youtube.com/watch?v=YQh2FQ7MZdA&t=22m51s ; timestamped for the specific question, but the whole talk is worth a watch