A tragic hero must have certain characteristics. The first is that he should be of a noble birth or have great wisdom. It is then that the hero realizes his mistake and learns from it. We should empathize with the hero, not despise him for his flaw. Many tragic heroes suffer death, but they face their deaths very heroically.
How does Walter Lee Younger resemble this tragic hero? Not born to nobility, Walter does possess a flaw in this character. He obsessively wants to prove himself to be a man, the man of the family now that his father is dead. To do this, Walter thinks he must prove himself financially and is willing to risk all the money the family has to get what he wants. Mama wants him to grow spiritually and be the good man he father was, taking responsibility for the family. Walter loses everything, the total amount of money, when his friend runs off with it all, and he's at his lowest point, and we feel his pain. When Mr. Lindner tries to buy Walter off so he won't move the family into the all-white neighborhood, Walter finally sees the cause for his downfall. Learning from his mistake, he rises to the occasion and refuses Lindner's money, bringing the family back together spiritually and emotionally.
At the beginning of the play, Walter is in a high place of self-control. Not only is there the prospect of the insurance money, but he also has an opportunity to make himself a business owner, independent instead of subservient. But then comes his fatal flaw, which is common to all tragic heroes. Through hubris (pride), he places his duty to himself above his duty to his family (with himself as part of that family). The tragic choice is made and fate steps in. His money is lost, his opportunity is lost (through a combination of his own choices and the choices of others), thus leading to his fall. Like all tragic heroes, his fall also causes the fall of others within his sphere. Much has died, but something remains (which is not true of all tragedy). There still remains a small sliver of hope.