As you're probably well aware, if you want to make money online you've got to have something to sell.
Now while there are a few shortcut to this - by selling someone else's product and getting a commission on each sale - OR - buying a ready made product and putting your name on it - both have their flaws.
When you don't control the product, you're never in charge of the quality or it's price. - If the owner makes a change and starts delivering a weaker product there's nothing you can do about it, other than stop promoting it. And if they lower it's price, your commissions also takes a hit.
Buying a product to put your name on, has it's own headaches. When the world and it's mother is selling the same product, you can't stand out from the crowd. And if someone decides to start giving away the product you now own for free, it completely wipes off any price tag you've attached to it.