When Amazon reaches a point that is unacceptable to you, you will pull your Amazon Prime account. Obviously, that has not happened yet.
When a grocery store begins stocking more alcohol, tabacco, and weed more than groceries, I would bet you would begin to look for another grocery store.
It's not complicated, and it's not a defined box of rules. We all would hope that a business entity would be of high character, integrity and morals etc. But, that line gets blurry...and we all have our own boundaries. One is not right or wrong in where their boundaries are.
But you already know this