Thing is that most higher level players didn't really receive help. They'd either make small groups/teams, or they'd level up on their own. So they invested a lot of time and resources into getting where they're at, while the circumstances were much more harsh. (I played since day 1 and there was no-one to mentor us, not to mention HBs and Nanas are much more available as of now.)
People generally have a mindset of "If I did it from scratch, what's stopping him?" At least that's the way I see it. I wouldn't mind helping someone out, but knowing that I've done all of that on my own without malling, or even no-lifing, means that he can as well, all it takes is a bit of good will.
Although the thing which personally most turns me down to help others is how they ask. I always try and help out people who ask politely and have at least a bit of humility, but when someone starts spamming local, your PM and become a giant pain in the ass, as if you must help them; or worse yet, you help them and then they start nagging you for every little thing, those kinds of things generally piss people off.
I know I might get a lot of hate for this, but it's how things are. Showing no good will to do things on your own as well as having no respect when you're figuratively "on your knees", begging for help turns most players away from providing someone with help.
