I think you may be misreading him, Chesterton isn't saying you should stop improving yourself, but that you can't hope to find that improvement in a book detailing the supposed habits of the wealthy and successful (or the one weird trick that makes everyone a millionaire).
Your goal shouldn't be to become Cornelius Vanderbilt, it should be to take advantage of your abilities and circumstances to find your own path to success.
Your goal shouldn't be to become Cornelius Vanderbilt, it should be to take advantage of your abilities and circumstances to find your own path to success.