The gist is that if you praise kids for being smart, rather than for working hard, they don't do as well, and in fact give up more readily, while kids praised for working hard rise to challenges more resiliently. The effect is pronounced and visible immediately.
This explains an awful lot. It explains a large number of people I saw in college (way more years ago than I care to admit now), and a lot of people at the dot-com where I started working at the leading edge of the bubble. It also explains a lot about my wife's (high-school) students.
Of course, everyone always thinks the next generation is callow and stupid and whiny and all that. But still. This time we have data.