https://www.businessinsider.com/amazon-seller-business-model-chokes-out-small-business-2021-5
ditto. I did a full analysis as lockdown hit last year of all Amz costs, and dropped it completely. It was pointless. The only person making money was Jeff.
I was always aware it was tight but held the belief that a customer was still worth having. The truth was different for me anyway. Few became regular buyers direct.
Perhaps I did not push them hard enough, but the numbers of customers were low and the basket size small. I am better of aiming for my own customers direct.