The point is: would you rather spend your time playing the game, or reading someone's stab in the dark on the mechanics of the game based on his/her personal experience and questionable expertise?
I can find out a lot of stuff on my own, but it never helps to read what someone else has figured out.
Analogy: I can figure out design patterns of programming on my own, but I can speed up the process if I read a book on it. Same with design patterns for happiness and success.
There are lots of things I consider possibilities now that were not even on my map before I read self-help books.
EDIT: s/never helps/never hurts/
Before I started reading self-help materials, I was intellectually gifted but I was a mess in terms of communication with others, emotional stability, self-limiting beliefs, knowledge of possibilities in life, luminosity aka self-insight, strategicness aka getting shit done with a plan, etc.
Studying self-help materials for the past 5 years is the most important thing I've done in my life (a quite dramatic statement perhaps, but that's how it feels to me).
That's why I get a bit upset and argumentative when people slam self-help: it's a bit like saying I shouldn't have wasted my time reading all those things, and instead should have just plodded on in darkness.