Your argument seems to conclude that:

It is impossible to reason with unreasonable people

Agreed. Now what?

Ostensibly your post is about how to swing the ethos of a large group of people towards behaving differently. I would argue that has never been necessary and still is not.

A good hard look at any large political or social movement reveals a small group of very dedicated and motivated people, and a very large group of passive marginally interested people who agree with whatever sounds like it is in their best interest without them really doing too much work.

So can rationality work on a large scale? Arguably, it always does work. I rarely hear political or social arguments that are obviously (to everyone) pure hokum. If you look at how the last 4 U.S. presidents campaigned, it was always on "save you money" talking points and "less waste, more justice" platform. All rational things in the mind of the average person.

I think however your implication is that rationality is not always obviously rational. Well friend, that is why you have to completely understand the implications of rational decision making in terms that the majority can agree on in order to describe why they are better decisions. You often have to connect the dots for people so that they can see how to get from some contrarian or "non-intuitive" idea to their goal of raising a happy family.

This is the essence of "selling." Of course spinners and politicians sell lots of crap to people by telling half truths, overcomplicated arguments or simply outright lying. These are obviously disingenuous. If you need to lie to sell your ethos it is probably wrong. That or you just aren't wise enough to make it comprehensible.