I realize it sounds utopic but it’s not nearly as insane as people think it is, especially when compared to mass boycott proposals.

To illustrate this point I will use meat because it’s probably the easiest to ditch of all major environmentally irresponsible behaviors. You first need to have a public where ~40-70% of the population is passionate about ditching meat, with most of the rest not caring and so falling into line. You then need to make sure that people who depend on the meat industry one way or another(which includes farmers/ranchers, fast food workers, people who cannot easily access vegetables, etc) are taken care of or understand that the overall social benefit to them outweighs the individual cost of ditching meat. You also need to have some way to coordinate this action to happen reasonably synchronously so that societal ideas about meat aren’t reinforced. This level of public organization and power is more than enough for things like general strikes or even regime changes.

You’re right, individuals can do a lot. We can take all of our politicians, CEOs, and corporate shareholders, and throw them out to one of their private islands that they love so much. Then, build a society where you aren’t pressured or even forced to drive, to replace tech every 3 years, or have a logistics system reliant on fossil fuels. Oh was that not the kind of public action you were talking about?