when a retailer puts a price on an item, that is the amount they reasonably expect some people to pay for it, that it ought to be worth that amount to someone. additionally, any product has an inherent value to the producer of it. the jaded among us can assume it's a fraction of the mark up, but every item does have some degree of value based on the cost of its production. when an item is marked down in price, and put "on sale," logically it is the retailer who suffers, as some of the expected profit is reduced as a compromise with a resistant customer. does it take away at all from the base value of the item though? if it costs less than before, is it at all worth less than before? for the customer who pays full price, the gleaming newness or the pleasure of perfection, or a need satisfied, all justify paying the full price.
if you knew an item or brand was never going to go on sale, would that make you more or less likely to buy it?