You don't have to believe it, but facts and hard stats make it more than plausible, and not to toot my own horn but once you taste some of this level of success you see it's more than possible.
I have 30+ products, and out of those, my top 5 did extremely well then I sold the network of those 5 sites for an additional $xxx,xxx, all within 10 months. Now I still do quite well with the rest of the products and new ones are always on the go. If you do reach xxx gravity and have at least a handful of super affiliates you go huge quick mate.
I know, the site is shit, believe me I've analyzed it over and over, even tried to make our own modern version of this as an offer (everloss.com). But you are a marketer not the end consumer so your view is skewed. Like I said they simply hit their customers perfectly. What looks like CRAP to you and I, the customer sees as a solution, a non-intimidating easy to use/click/read/buy solution. For whatever reason, from font to choice of branding, to market entry (one of the first many years ago), to market share.
The product itself is NOT that great compared to what's out there - however the front end simply works, and works well - here look at their stats too - http://www.nichejunky.com/product/4idiots even the alexa ratings indicate a shitload of traffic, and once you start promoting this or similar weightloss products, you see that they are EVERYWHERE.
Don't fight it because it seems abnormal or unreal, it's more than possible and is quite influencial.
They don't do anything different than any other publisher tried/tries to do. They simply did it at the right time and it will be HARD and take a LOT of money/time to take over this niche from them.
N.