If you're someone who's grown up with a poor education, can't afford basic healthcare, has an absent parent and/or a neglectful one, and find yourself in a position where you're having to scrape by on a minimum wage job that barely gets you by then it'd be easy to see why you'd adopt a pre-defeatist mentality. Especially if someone better off than you says that you just have to 'work harder' to succeed when they're ignoring the fact that their chances of success are boosted by the fact they had a better upbringing and (if they're from a fairly rich background) will be able to make contacts in high places with greater ease due to their parents etc.
I don't deny that people can work hard and succeed...we've seen plenty examples of that happening, but I'll have sympathy with someone who's really, really struggling to get by when they've probably suffered from a lot more than I'd be able to imagine. In such cases giving up doesn't strike me as being 'pre-defeatist,' it's just someone accepting that due to the system in which they operate their chances of ever succeeding are minimal compared to people who already have money behind them.