Agreed with the first part of your post, but you completely loose me at "stop buying shit" being a solution.
Any meaningful massive change requires systemic and legislative frameworks that companies, political organizations and government entities have to abide by - and this framework basically modulates popular behavior. Ex: what's available for purchase (ex: only things meeting certain profit margins or environmental criteria), who you advertise to and what you can advertise (ex: not to children, not for medication, etc), etc etc
If we expect and hope people to "wake up" and change their behaviour en masse, it's simply never going to happen, and the large corporations and lobbies keep rubbing their hands, happy we're guilt tripping each other rather than vote in people with clear legislative and regulatory agendas focused on actual human well-being...
It's like an engineer imagined a perfectly spherical consumer: it makes only rational decisions and, once that decision is complete, it retreats into a hermetically sealed box to wait until it is time to make the next perfectly rational decision.