Science has very solid evidence on social networks being extremely addictive, and there are growing suspicions that some companies have it like this by design. It might be a choice, yes, but this is not a black-and-white situation.
That is completely ridiculous. Obviously literally every social media company wants to generate sustained user engagement, this isn't a "growing suspicion" it is their business model to act that way.
Their entire purpose is to maintain engagement, it's not a conspiracy.
Even scarier, this doesn't even have to be conscious on part of anyone running the companies. There is no need for bad intent. Simply optimizing for engagement leads to addictiveness.
(I'm not saying there's no bad intent, just that it's optional and we're screwed even without it)
In that case, I beg to differ, it is not cheap. When we are talking about highly addictive platforms, this is a zero-sum game (in which every second spent benefits the platform and only the platform in detriment of the user's own health).