Why is Macbeth a tragic hero ?

Tragic heroes generally share a group of similar characteristics.  They are as follows:

1. The character is of higher status or nobility


2. Although the character is noble and great, the character has to be relatable to an audience


3. The character is at fault for his/her own downfall.  The downfall is usually triggered because of some character flaw.  Most teachers refer to that flaw as the "tragic flaw."  


4. The hero's downfall isn't entirely deserved, but the hero does recognize that his downfall was his fault.  

I believe that Macbeth easily fits three of those four characteristics. 

When the play begins, the audience is told that Macbeth is great in two ways.  First he is a member of the ruling class.  He is a thane, which means that he is most definitely not a lowly servant or common foot soldier.  The audience also learns that Macbeth is indeed a great warrior with extreme amounts of bravery.  

For brave Macbeth--well he deserves that name--
Disdaining fortune, with his brandish'd steel,
Which smoked with bloody execution,
Like valour's minion carved out his passage
Till he faced the slave;
Which ne'er shook hands, nor bade farewell to him,
Till he unseam'd him from the nave to the chaps,
And fix'd his head upon our battlements.

I do believe that Macbeth is a relatable character.  I believe that he is relatable, because he is subject to temptation.  The witches prophecy that he will be king some day and that tempts Macbeth greatly.  It would tempt most people.  Even if a person could honestly say that being a king is not tempting, I can guarantee that person has done something dishonest in order to satisfy some kind of temptation.  He's relatable, because he is not perfect.  He's relatable, because he experiences emotions and temptations the way that the rest of the audience does. 

Being not perfect applies to Macbeth's tragic flaw.  His flaw isn't that he can be tempted.  His flaw is that he has unchecked ambition.  For Macbeth and Lady Macbeth, the end justifies the means.  He is willing to commit murder in order to obtain a higher status and more power.  He's ambitious to a fault, because his ambition causes him to abandon his morality.  It's Macbeth's ambition that eventually leads to his downfall.  

As for the remaining tragic hero characteristic, I do not feel that Macbeth fits it.  I believe that Macbeth deserves every bit of his punishment and death.  After killing Duncan, Macbeth had several other men killed in order to further secure his place on the throne.  I believe that Macbeth got what he deserved for his murderous acts.