Compared to how important and how ignorant most people are about issues like topsoil degradation or peak oil, I don't bring it up often. I don't think most people are primed to hear much doom and gloom other than climate change or Trump, so I imagine my concerns will fall on deaf ears. But occasionally I'll go there.
Today was a pretty typical example. I was having lunch with a coworker and I decided to bring it up. I don't know the guy well, but he seems interested enough in social justice and environmental topics. So I kind of briefly mentioned likely collapse trajectories, gave him a moment to respond but he seemed to be processing the info, so I left it off there. Maybe I planted the seed of doubt about industrialism's future. Maybe he's already forgotten. Either way I think this may be the better approach than getting preachy and perceived as a wingnut.