Baal HaSulam, “Introduction to the Book, Panim Meirot uMasbirot,” Item 20: Because of the sin with the Tree of Knowledge, the impure forces were given control over man. This is why the order of the universe is very confused. Sinners beget evil, decreasing the Light’s abundance for the people. This naturally leads to destruction and suffering. But if they increase the abundance, then the separation for the receivers increases even more, as the sages said, "If a person has one hundred coins, he wants two hundred, and if he has two hundred, then he wants four hundred."
It is man’s nature to always chase pleasure, but by doing so he only increases his desire to receive. All of life is an endless pursuit of pleasures which you can never attain. And the small bits of fulfillment that we do receive are given to us so we would keep pursuing and increasing our desires.
It seems to us that we run after pleasure, but we are running after even greater desire! We barely touch our object of desire, and the next moment we feel that we need twice as much! When we experience pleasure for a moment, we increase our desire two-fold, and thus the pleasure itself turns into desire. This continues on and on until we grow disillusioned.
From the 4th part of the Daily Kabbalah Lesson 7/19/10, “Introduction to the Book, Panim Meirot uMasbirot”