Why? Don't they both sell other books on cracking and pentesting and whatever? There are tons of videos on YouTube about hashcat and aircrack-ng and rainbow tab

Why? Don't they both sell other books on cracking and pentesting and whatever? There are tons of videos on YouTube about hashcat and aircrack-ng and rainbow tables and blah blah blah. You think this stuff is some kind of secret or illicit knowledge? The video is just less than half a minute of him flipping through some pages in the book anyway.