It's also a matter of
A) rewards. If you're going to put 10x more work into something, then you'd expect the rewards to be worth it. That doesn't mean only salaries (though that sure helps too), but also stuff like overall job quality, social recognition of your efforts, etc. I'd say that in the west, for various reasons and to various degrees, all of those gradually declined.
We went for example from a culture which put its intellectual elites on pedestals, to a culture where being technically illiterate or even outright stupid, is cool and fashionable. In fact, if you show any intelectual interests or aptitudes, it's kinda mean of you and insensitive to your below-average neighbours/classmates/etc.
In programming alone we went from being those wizards doing high tech stuff, to being outright disconsidered. Nowadays for the average outsider it's not "I don't know how to do the things he does", it's more like "I have a life, I don't have time for that crap" or "yeah, the neighbour's 12 year old can do that kind of stuff." The idea from the 90's that you can just retrain an unemployed pizza-delivery-guy or burger flipper off the street, and he'll be just as good as those snotty CS and engineering graduates anyway, also didn't do much for recognition. It was hammered in everyone's head that you _are_ no better than him, and he could have had your job too if only he could be arsed to take one of those two-week java courses.
Now not all countries are at the same point, and not all went in that direction as fast, but that was the general direction all went slowly.
That's one reason to put in the extra effort, that went down the drain right there. For a lot of people that criterion is now actually a disincentive, since all that extra effort might actually _lower_ their prestige in the community instead of raising it.
B) Rampant age-ism also doesn't help. Back then, sure, I was young, I thought I'd never get old. When 15 years is your entire life so far, and you probably remember only 10, living another 45 years to 60 seems like a bloody eternity. No point worrying about something _that_ far in the future. Now I see perfectly competent programmers pushed aside or into a corner, because some PHB learned the mantra that only the smart young kids are any good.
If I had a kid, I'd tell him to stay well away of that field. Chances are you _will_ live to _at_ _least_ your 40's, even if you chain-smoke and get to twice your idea weight and go alcoholic too. If you want a job where you start being discriminated against as early as the 30's, heck, go into prostitution or porn instead. (And considering some bosses I've occasionally seen, prostitution might even be the more dignified job.)
C) It's also a matter of, well, excitement.
In all science or engineering domains, there was a time where it looked like there's so much interesting stuff to do or discover, and only the sky is the limit. (Or in aerospace not even the sky.)
In programming, for example, when I looked at some primitive games or programs on the old ZX-81 or later ZX-Spectrum, I thought, "I can do better." Often I actually could. Heck, I could even paint my own sprites by hand, although I'm no graphics artist, and they still looked good enough at that resolution.
Nowadays, if I look at a modern game, well, there's just not the same sensation. Duly noted, nowadays about half can be modded, so you can still tempt someone to programming that way. But for a while even that wasn't the case.
Ok, so that's only games, but the same applies to any other programming domain. At some point you could have been the guy who created the next big language, wrote the OS for some underpowered mini, or did the next great maths thing with a computer, or designed the next computer itself, or whatever. Nowadays you'll be a cog in a 20-people team writing the front-end to some database app.
Or if we move away from programming, as I was saying, the same applies to any other engineering domain. At one point we had the people designing car engines be the gods of engineering, and making breakthroughs left and right, while nowadays it's a team of peons applying formulas and tweaking the injection pressures. Chances are that the designer making it visually appealing, or the marketer coming up with the ad campaign for that car, actually make a bigger difference to that car than any of the guys who worked on the engine.
It all just doesn't have the same ring to it, ya know. "If you learn and work hard, you too could be a faceless, unimportant, expendable, replaceable worker at a glorified assembly line" isn't quite as motivational as "You too could make the next big thing."
I suppose it's inevitable, and I certainly don't propose to remain frozen in the past. But then let's not wonder if people aren't as motivated to get a degree in it any more.