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Just like the other MLMs (or rather pyramid schemes, because that's what they really are), they sell a (unprofitable) lifestyle using deceptive marketing. The products are secondary (they're just there to keep regulators at bay) and are always sub-par and inferior to what can be found off-the-shelf.
Furthermore, most of these luxury goods have actual value. Even if you are stupid enough to go into tons of debt and fill your garage with Harleys, there will be plenty of buyers who will be happy to take it from you at a small loss. In comparison, nobody will buy a garage full of Herbalife - the cost of shipping would be more expensive than the market value of the product itself.
It's basically just a better marketed MLM company, I first realised about the MLM part 12 or 13 years ago when I went to one of their presentations in my city (got out as soon as I could), which I guess leaves them with the "better marketing" part, which I admit they're pretty good at (if I'm not mistaken at some point they were sponsoring the football team AC Milan and the football player David Beckham).
"Fake it til you make it" isn't just for tech startups. A lot of companies juice results with a bit of fraud, but eventually get good real results anyway. It's hard to tell the difference between an outright fraud and a healthy company with aggressive accounting.