If those who can afford it would do it, like the well-off people frequenting hacker news, that would be a start. That would drive up demand, make it worth for more farmers to do this sustainably, eventually driving those costs down, and thus making it more affordable for lesser income people. And it's not black and white, in each iteration more people can afford it. Similar to electric cars.

It's easy to armchair-philosophise those things away with "oh but poor people wont ever have the money, so screw it". With that attitude we'd never hav gotten electric cars. Or solar power.