As a fellow American, I also just eat a few hamburgers per year. I actually prefer non meat burgers to regular, though I love high quality meat (though I don't it it very often). I like to primary source stuff and can't find a hard, verified number in my limited Googling, but as far as I can tell our consumption is incredibly low compared to the per capita average (over a hundred per year, into the multi hundreds per year depending on region). The key is not to get people who are eating 2 per year down to 0, but to get people eating hundreds per year down to, I dunno, 10? Either way we can picture a sustainable economy in which high quality plant based meals are cheap, and then everyone gets their high quality meat meals less frequently and for an amount of money that is commensurate with their ecological impact.