It's not just Dr. Mercola telling us this obviously.
This shows that you obviously didn't look very hard at his website. There are a handful of things for sale because that is the only place they are offered, but it is not a commercial site, it is an information site. There is no advertising from vendors, no popups, etc. Dr. Mercola has a staff that run the website and he loses money on it, he is only doing it because he believes in getting the info into the public arena for discussion.
As I said, if you had looked over the website very much at all you would have alreaady found this out. But it's easier to stick with your own ideas than to have them challenged.