In the health niche, how do you keep promoting the same products? If someone has has an illness, you can only throw the same e-books or Amazon links at them before they heal or unfortunately pass. And I'm assuming you would have to target a certain health related issue to get them on your list in the first place, so you couldn't promote every heath product under the sun.
And have people not figured out there are millions of videos on YouTube showing you different exercise techniques? You don't need a $29.00 course anymore. All free stuff out there.
In the relationship niche, how many books can one person read to pick up woman?
Am I missing something? Or do people enjoy buying e-books since they figure there might be that secret golden nugget they just can't get in free information?