Willie Loman's decline follows his growing sense that the system upon which he has staked his life and dreams has betrayed him. The American Dream of personal and economic security following on from hard work and professional integrity falters as payments fall due for car or refrigerator or house. The underlying problem is that the profession on which Willie staked his life, that very symbolic role of Salesman, is ready to toss him aside, while the world modernizes and the old notions of character and personality fall by the wayside. It is something that we may be accustomed to in a world of corporate downsizing and shrinking profit margins. But it is a terrifying new aspect of Willie Loman's world, built on different principles for much of his life.
Management is more aggressive, less intimate.
One can no longer make one's mark through personal charisma . But for all his doubts Willie will not publically own to this betrayal. He still offers up his son in a strange kind of sacrifice to the god of material success. He condemns Biff's wandering under the open skies of the American West as a kind of delinquency, though as dreams go, perhaps Biff's is as valid, or more, as his father's. Willie tries to pass on his dream to his son, but fails for a series of fairly obvious reasons.