Moreover, the author does say that people who seek to get rich are greedy, and not only that, but that they are trying to succeed by being greedy, rather than by "good work":
But what shall we say of the gospel preached to the new Industrious Apprentice; the Apprentice who rises not by his virtues, but avowedly [self-admittedly] by his vices?
If you acknowledge there is skill in succeeding (with a company, say, or in overcoming a bad habit, or tending your goals and beliefs, perhaps even to train more rigorously for that high jump), and that these things are moral or at least not immoral, the author's argument falls apart. It's as if he spins around and says that the best whist players and bricklayers must be propelled by an unhealthy greed or pride, seeing as it's impossible to write a book on such mystical things.
We recognize today that money is not moral or immoral, but amoral. Perhaps it is dangerous that the economy is one big, somewhat arbitrary game, but so be it. We should see it for what it is.
As for self-improvement, I look forward to collectively pulling back the curtain on the human psyche more and more, continuing a pattern of ever-enlarging consciousness and awareness, shedding light on what was previously mysticism. From this perspective, the author just seems to be saying, "Stop, there's nothing there. Don't sail that way or you'll fall off the edge of the Earth."