This is generally because either it makes sense economically (YouTube dropped video distribution costs to zero), you avoid some unpleasantness (grubhub), or you're psychologically manipulated to more or less be addicted to a service (Facebook) -- in many cases all of the above. Network effects of going vegetarian are minimal, and have been since there's been meat.

It absolutely needs government intervention. For decades scientists have been warning about climate change and diets have not changed. If you look at any region with meaningful impact you'll see it's 100% due to regulation, whether that's penalties for bad garbage practices, penalties for water or electricity waste, etc. There is simply no way we crowdsource this, and my evidence is that we've had almost 40 years to do it and haven't even come close.