What is the harm if a person pays $50 for something, and $50 for something with a 50% off sticker next to it? The latter just releases some chemicals in the purchaser’s brain maybe making them feel better.
Vendors don't put the 50% off sticker on it to make those happy who would have bought the item anyway. They put it on to trick people who would not pay 50$ for the article into doing so.
The fact that they paid $50 for it seems to negate the claim that they wouldn’t pay $50 for it.