In a market ecoomy, a high price is a signal for producers to supply more and consumers to buy less.
Think of a high price as saying to producers, "Go, go, go!" There is obvious demand for the product that has pushed the price high--so the more you can make and sell, the more you as a supplier will profit. At the same time, the high price is saying to consumers, "Whoa, whoa, whoa! Slow down!" High prices will tell consumers to hold off on purchasing something and assess whether they really need it or can afford it. Even if the product is needed, consumers may wait, in hopes that prices will come down before long, or buy less of the product than they would have if prices were lower.