Yep, that's a great question I kind of wanted to bring up in the post as well, but it was getting long.
Because it calls into question things about how much money Tim makes, which is sort of none of my business, but since he writes a book and blog about how you can be basically make more money more efficiently, it sort of becomes interesting to me.
Does he need the supplementary income from Amazon because he doesn't make enough from his books + lecturing + investing?
How much money is he making with this kind of thing?
And maybe it was sort of unintentional to post an affiliate link and his Wordpress installation just auto links those somehow?