I think that SM can be lifelines for a lot of people, a ‘hobby’ or pastime for others, and yes, an addiction for some.
I don’t think we can extrapolate our own experience onto others, though. 8 hours a day on SM might be a shocking idea to someone who works, or who is out and about a lot; but to the housebound, or to someone living alone they can offer different views of life, and a chance to connect with others that might be otherwise unavailable. I think that interaction on SM can be a lot ‘healthier’ than getting one’s views from newspapers and/or broadcast media, yet I know several people who think that reading the Guardian and listening to R4 news means that they are better informed.
Sometimes, and about some things, maybe - our experience of SM are limited to the range of contacts we have on there - but IMO chatting to people who are living through things that are simply being reported in the press can be a lot more enlightening than reading or listening to mediated accounts. Look at the thread on here about claiming benefits, for instance. People who don’t have experience of the benefit system are going to learn more from that than if they read an article in a newspaper, whether that article is supportive towards claimants or otherwise, and crucially they can ask questions if there is anything that they don’t understand or want to know. That’s just one example, the same is true of so many other topics, so long as people don’t screen out views that oppose their own.