Tubberware, is also a firm, with actual products.

• The only reason it's not called a ponzi scheme, is exactly that, they have a physical product.

Now, I'm not saying, that it's a bad product. Nor am I saying, that it's impossible to earn money from it.

• But it's still a scheme.

I'm too tired right now, to actually go into more detail. But I can recommend Penn and Teller for at least the base knowledge.
^ Unless you're one of the actual money grabbers, then just ignore it. ^_