There's no doubt that if you work really hard (I've got colleagues who pull 80 hour weeks routinely, which I consider excessive, YMMV), then you will definitely do well in science. If, on the other hand, you are like the majority of people and go for a more even work-life balance without all those sacrifices, chances are that at some point you will get stuck in a low paying postdoc, moving from project to project, never really sure that you have a job for more than the next year or so and a salary on which you can't really support a family.
This trade-off is there in every profession of course, but I find it's a lot more exaggerated in science and technology than elsewhere. That being said, there are of course lots of places where a good work/life balance is possible and where sensible career choices are available. I do think we shouldn't kid students towards believing that it's some sort of cakewalk though. It's grueling and sometimes thankless (like being labeled a parasite by the common tax payer, always fun).
Of course, a science or technology degree is usable in lots of industries, so you're not really limiting yourself that much by getting one. Compare this with people pursuing an english degree, where there are so many more candidates than positions at the postdoc level, and you wonder why anyone would still bother.