We can boycott the rich. And when we cant, we can just choose to buy from the least rich
Try. Boycot banks by giving them no money, maintain social lending in your local area, see what happen then.
That sounds more like a theoretical solution than a practical one. You'd need to get most of the population to ignore short-term convenience and pay higher prices for things (optimizing for a different metric than lowest cost). I don't think that will happen.
Just saw your comment. You beat me to it. Here's mine, though, which provides a key detail: