I don't know about you, but when I'm comfortable like I don't have to worry about freezing to death in the winter, I'm happy. YMMV.
To repeat the t-shirts/bumper stickers: people who say money can't buy happiness don't know where to shop. And while it's true that money might not be able to buy perfect happiness, it will certainly buy a better brand of misery.
Without going in deep, just a point of order: A lot of less-than-ideal outcomes that certainly are traceable to a choice someone made...trace to a choice that was perfectly rational at the time. Say you get offered a job a thousand miles away - it seems to be a very good position that will afford an income good enough to cover a higher cost of living, a mortgage instead of rent, a better way of life all around but it means cutting all support available where you are. So you take it. A year latter your new employer goes bankrupt, you walk out the door with nothing, and in the mean time the local economy has gone south somewhat and there's no obvious job, certainly not at the former income level - not enough for that mortgage. Point being, making the "right" choice by any available measure can still fuck up your life.