Basically everyone who works for Facebook. Think of the time it takes away from society and what that time is worth. Compare that with the pittance in advertising income they earn off it. That's more inefficient than a thief who steals jewellery and sells it for a tenth of its value. I don't think the small benefits from Facebook come close to the tremendous harm it does to society.
I closed my Facebook account years ago and have never missed it. I'm a lot richer (literally and figuratively) for not having wasted a thousand more hours on it.
I get that Facebook is a solid target to pick for such a rant but frankly it's a tool like any other. Blaming Facebook for potential productivity loses due to its addictive nature is like blaming hammer maker for all deaths it caused. My dad doesn't have Facebook but he definitely spends his spare time watching TV or sports that can be considered just as wasteful.
I closed my Facebook account years ago and have never missed it. I'm a lot richer (literally and figuratively) for not having wasted a thousand more hours on it.