Ask HN: What concepts, if popularly understood, would most improve the world?
A personal list would start with an understanding of cognitive biases -- how they can be formed, how to recognize them, and how to work with and around them.
I have noticed my mood is tightly tied to my diet and living conditions.
But a real answer might be a set of concepts around self-management, that you'd find in a Christian self-help book, or stoicism, or Buddhism, or the rules of St. Benedict, something in that category. But if you look at the uselessness of "mindfulness," maybe not.
I do this internally (not quite to that extent, but along a similar line of reasoning) all the time and feel a little bad about it, yet even as I type this I can't help but feel it's true in many cases. I have a low tolerance for people that abuse medical diagnosis as a certified scapegoat (a static, unchanging one at that), and most of the depressed people I've known don't eat well, exercise regularly, try to sleep better (get off your phone/laptop at least an hour before bed, for example), or perform any other anti-depression-101 tactics. I have pretty severe bouts of apathy at times, and I feel that depression is often a case of simply indulging this apathy a little excessively, while postponing the work involved in constructively and pragmatically working one's self out of it.
On the flipside, I tend to agree with the idea that our current model of society and the direction it's going is incompatible with a happy life for a lot of people, and it's perhaps no more fair to blame them for this then it is to blame a square for not fitting into a circular hole. But, if you dull your corners enough, you may just fit right in.
At any rate, this was largely tangential and irrevelant, I'm not intending to dispute milestone #2 in a general sense and thanks for the link - it's a good read.
My mother-in-law used to work full-time for a hospital calling insurance companies to get them to actually pay for claims.