It always disappoints me that entrepreneurs seem to read very little.
Part of the problem is that they don't seem to understand the wisdom which they can extract from a well written book.
The ROI you can get from reading a well-written book, as far as learning goes, is far higher than any other investment of your time, energy, or attention. The big problem is that most founders don't have good reading habits. Most are passive readers, who read all books as novels, and this dysfunctional approach doesn't help at all.