On the other hand, some fraction of people are going to gamble away their life savings on bad bets. No idea how you balance the two, but gambling addiction does have a human cost.

It is admittedly not that much different than any other addict looking for their next fix. Yet, if feels lot uglier when it is a billion dollar corporation on the other side optimizing for the human tragedy.

Sure, and I actually have less of an issue with gambling than I do with social media companies and indeed advertising companies in general, but in both situations it's a massive unaccountable corporation abusing people for profit.

Lot’s of people win from Facebook as a communication platform. It also does all kinds of explosive crap, but being able to keep up with distant family and friends has meaningful value.