> It's like if the #1 grocery chain removed all the addictive stuff. No junk food, no soda, no alcohol. In the short term, people might consume less bad stuff. But in the long run, the #2 chain would take over, and we'd be back where we started.

What you are observing is a case where market signals result in obviously undesirable outcomes. The problem cannot be solved from within the market, the market's signaling needs a tweak. In the case of this example, a tweak to bring purchasing behavior inline with what people want to be buying in the long term, what they know is good for them. This could be achieved by mandating some form of friction in buying unhealthy food. Banning outright tends to go poorly, but friction has seen great success, like with smoking.

I'm not sure exactly what this looks like for social media, or if it's even a necessary form of action (would banning surveillance-based advertising kill feed-driven platforms as a side effect?) but as you say, the market will not resolve this even if an industry leader tries to do the right thing.