Is Amazon wholesaling even legal?

I’ve been looking into the Amazon wholesaling business model and unless I’m missing something, it sounds pretty sketchy and very high risk.

You build a “wholesale website” and then try to convince large brands that you are a reputable wholesaler so you can get their products for the low, giving them the impression that you will be reselling them via a wide range of channels.

Then, you sell their own inventory through their listing on Amazon, taking a percentage of profits that they wouldn’t have had to share if they just sold directly through the same listing without you.

Those companies are agreeing to let you wholesale their goods because they think you will bring them sales they otherwise would not have had… not just suck money out of their existing listings that are already producing revenue.

Am I missing something here? How are wholesalers not getting hit with cease and desist letters left and right?