As a follow-up comment, I will say that anyone who self-publishes a book is taking on a second career as a publisher, marketer, and distributor. So kudos to him for following through and realizing a second edition, complete with improved proofreading and distribution to appropriate sales points like pipe shops.
If the authors don't work their asses off distributing the book, they'll end up with a garage or self-storage unit full of unsold books.
Some online self-punishing outfits make the process easier, printing copies only on demand, thus letting the manuscript survive on a pay-as-you-go basis. It is still expensive, but more attainable than the old running full editions in thousands of copies before there is a readership established.
Self-publishing is not to be confused with vanity publishing, in which case the author is paying a company to print, market, and distribute their book instead of paying the author for the privilege of doing so. This is a racket worked on writerly egos and is usually a pathetic scam. Self-publishing is simply paying to have the book printed and selling it yourself. Many esteemed authors started that way.
So whatever you think of Hacker's work, I'll give him credibility for doing the publishing part himself. That alone is a big deal.