Dead

When Willy gets into his car while Biff and Happy are listening, he goes crazy and does some weird things, and he eventually dies in an accident. I think that by purposefully dying, Willy ends his misery. He tries to justify his death by saying he will do it for the $20,000, which to a certain extent is actually true, but deep down, Willy does not have enough will power and desire to keep going. He knows he is unsuccessful, he had just been fired, he ruined his son's life, and he, in general was just a crazy guy. I think that it was not his fault that he died. He could not control it and there was nothing that he could do about it. He was not weak, but he was also not a hero. It just sort of happened. Every lie and exaggeration he told, and every dream about himself that he made up amassed together and eventually built up, and in the end, this bubble of fake lies and dreams popped and he went crazy. He could no longer be the positive dramatacist that he was. Everything caught up to him in the end, and he could not deal.
So, in the end it was not a weak thing of Willy to do, but rather something that was inevitable. He in general was a crazy person. It was his destiny to die the way that he did.