In Tyler Durden's mindset, self-improvement makes one feel good temporarily (like masturbation), but provides no lasting fulfillment. Argue with Tyler if you like -- just try not to get punched in the face while you're doing it.
Whether or not this is intended to be an indictment of self-improvement in general or just the way most people treat self-improvement is something we'd have to take up with Tyler.
Clearly, Tyler believes that people should look inward for enlightenment and chase their dreams (remember the scene where he threatens to kill the guy if he doesn't go get his dream job?), so it's not as though Tyler Durden believes in standing still and stagnating.
Tyler would advocate the tough road to enlightenment over the latest self-improvement pop novel. I believe his motto might be: Self-improvement through pain and deprivation (which, incidentally, is at the opposite end of the spectrum from the fleeting pleasure and indulgence of masturbation and the temporary feel-good benefits of many self-improvement activities).
Remember, we're talking about an extreme individual who's idea of real self-improvement involves chemical burns and blowing up one's own house. But even if we ignore the character's insanity, it's pretty clear that his lesson is a good one: real enlightenment comes from hard work, introspection, and devotion to something higher than material wealth.