We used to be a big huge sellers on Amazon. Big. We had a basement warehouse and bought by the pallet fulls. We used FBA on Amazon… sending in shipment after shipment of product. In fact, at one time we had more product in the Amazon warehouse than in our own stock.
We also sold direct to consumer, which was a bit of business. We sold locally by delivery and nationally by mail.
It sounds like we should have been rolling in cash but we were not. Amazon was tricky because we sold a commodity product that others could also be selling. Lowest price wins, and many sellers would sell for a loss. So we took a different tactic, we started selling items that were soon to be discontinued or were already discontinued, buying up a large portion so we could outlast the other sellers. Sometimes we won, sometimes we lost. We gave away a lot of product that our buyers did not want.