There's a wonderful thing called «crab bucket theory» — which, in short, implies that crabs are socially stupid: one crab placed in a bucket would easily get out of it, while a bunch of such would grab and pull each other down.
When one tries to quit smoking, his friends will go "won't work, forget it" and hand him a fag instead – crab bucket. When one's going for a second higher education, his colleagues will argue "why, aren't tired enough at work?" – crab bucket. When one's own parents tell him they're being foolish (loser, mediocre, nothing's gonna come outta that) — yep, crab bucket.
It is in the human (crab) nature, can't help it, except one thing – overcome the bucket, no matter how many others pull you back.