I think these are all valid points. Here's what I have to add:
1. Absolutely, churn and burn is the name of the game. Retail is intentionally set up like boot camp or hazing for pharmacists to weed out the weak. So it's not about whether you can get a job because really, as long as there is an opening, they will hire just about anyone. The real test is whether you sink or swim.
But even if you do survive, I don't think you should just hang around swimming in the shark tank forever. Otherwise something like point #2 could happen to you. I guess the long term objective is to fight your way out to move up to a position like supervisor or move out to a cushier setting like mail-order. Or, you could just be a masochistic sicko and like being abused. In which case, more power to you, because you can always find work doing a job that everyone else hates.
2. Oh yes, I've personally seen this happen many times. One day they're posing for photos, shaking hands with the supervisor for their 25 year service anniversary. The next day, they're packing up their stuff because they got fired. You can never let your guard down, or get too comfortable in retail. Especially with the old veterans, the minute they start putting up an attitude that they want to do things their old way, or don't want to get squeezed anymore for higher script count, then that is when the sharks get unleashed on them.