Why does "was $149.99, now $89.99" feel so good, even when you had no idea what the product should cost in the first place?
Psychologists call it anchoring. The first number you see sets your sense of what is normal, and every number after it gets judged against that anchor instead of against reality. It is one of the most reliable effects in behavioral research, it works on experts who study it for a living, and retailers have known about it for decades. It is why the "was" price exists at all.
The trick, step by step
A seller lists a product at $89.99, its ordinary price. Sales are fine. Then the seller raises the listed price to $149.99 for a few weeks, sells little, and "discounts" it back to $89.99 with a badge announcing 40% off. Nothing about the product or its real value changed. What changed is the anchor in your head. The same $89.99 that felt ordinary now feels like a win, and the urgency badge suggests the win is temporary.
Knowing about it is not a defense
This is the humbling part. Anchoring works even on people who can name it, the way an optical illusion still bends even after you have seen the ruler. Willpower is not the answer, because the effect operates before deliberate thinking starts.
The only real defense is a better anchor
The fix is not resisting the number; it is replacing it. What did this product actually sell for over the past year? That single fact dissolves the trick instantly. If the answer is "$89.99, most of the time," the discount is a costume. If the answer is "this is the lowest it has been in a year," the deal is real and you can buy with confidence. Either way, the evidence beats the anchor, which is why putting that evidence in front of you at the moment of purchase is the entire point of what we build.