it's entirely possible Amazon did this math
I spent 2 years generating over $1mil a year in sales through the Amazon affiliate program - to be dropped without warning or contact. No amount of follow up and attempts to contact my, previously very accessible, account rep resulted in anything. Not even an explanation on why my account was closed, outside of being told that I could take legal action (in the state of Washington) against Amazon to collect on the nearly $40k in yet-to-be-paid earnings.
It wouldn't be a big deal if this was an isolated incident but it's not.
But people continue to sell on Amazon because that is where the customers are.
[1] Reserve means an item is unable to be bought, either because it's in reserve for a customer order that hasn't shipped or its being transferred to another warehouse.