... people tend to adapt to their situation. We might look forward to getting married, or dread widowhood, but within a few years of both events we are as happy as we were before them. This suggests that what we want rises or falls with circumstances. As G. K. Chesterton said: “No man demands what he desires; each man demands what he fancies he can get."
The context of this discussion was not Buddhism, but I got to thinking about it by way of the quote at the end there.
Let's start with the implications of the quote itself. What Chesterton is saying, if I'm not mangling it too badly, is that our desires tend to be in line with our expectations, because that's a potential strategy for maximizing payoffs. Who here knows the expression "if you can't get five, take two"?
What the larger article is saying is something I've been intuiting for a while as well: we tend to overestimate the impacts of things we think will be big, and underestimate the impacts of other things. But our brains tend to seek an equilibrium whenever they can. Hence the Chesterton quote: we tend to modulate our demands (although not our desires) to be in line with what we know is realistic.
In other words, our actual desires are much bigger than our demands. We know this, and we resent it to some degree, but we live with it anyway.
A lot of what Buddhism is about is retraining the default assumptions many of us have about desire. Most of us think our desires are ourselves — that if we stop wanting things, we'll shrivel up and die. That's a gross misunderstanding of both our selves and our desires, but for a lot of people (and for big swaths of society) it's convenient to keep this myth alive.
The big lesson I got from my own studies into Buddhism was that you don't lose anything if you decouple your self from your desires. You can still have goals and big dreams and all that. The difference is that you're not less of a person if you fall short of them; you're not turning the outcomes of seeking those things into a fruitless morality play. You can still want things, but you know better than to think you're nothing but that wanting.
It sounds terribly dumb and obvious when laid out like that, but if it was really that simple, how come more of us don't do it? Maybe because it isn't simple, and most of us are too caught up in the morality play of the self, I guess you could call it, to wonder what else might be possible. We fancy what we can get, which is mainly the satisfaction of our palpable desires; we don't tend to demand the biggest desire of all, which is not having to let our desires define us.