Well I don’t agree with what teachers tell us. Hard work can get you somewhere yes but it wouldn’t be the only thing you should do in order to succeed. In my opinion you need a little bit of luck still. Hard work plus luck is the deadly combo. That would get you anywhere you want in life and further. Though not all of us gets that lucky.
I agree with you, success takes more than hard work. Some would say "work smart and not hard", which means we should be resourceful as well, but even so, luck plays an important role in whether someone will succeed. So yes, having some skills and some luck is a winning combination.
Here my question is why they are not able to change their fate after working so hard...
I don't think this question has a simple and universal answer. It's a big world, and people must do all kinds of jobs to survive... Often these "regular" jobs are the only choice and that's what we have to accept.