Well, it's no secret that people can make money by doing affiliate marketing. The problem is that, in order to make that money, one needs a lot of traffic, and not just any traffic but targeted traffic of people interested in what's being promoted. That's the tricky part. Since you're an established content creator, with established traffic channels, it's no wonder that you can present affiliate offers in front of a large number of interested people. So, no matter how good an affiliate product is, without an appropriate audience, and of decent size too, no significant money will trickle in. So, anyone thinking about making money this way should first think about having/creating a reliable source of traffic.