For a figure to qualify as a tragic hero, he or she must possess some qualities of greatness. These qualities can be derived from nobility of role (as in kingship), but are not necessarily guaranteed by nobility of role. Is King Lear a hero? Is he a noble figure whose suffering can be construed as noble suffering?
I did not feel particularly sorry for King Lear until the end of the play when he had lost his daughter Cordelia. Then I did feel sorry for him, as I would for any man who had lost a child he loved. I was also moved by the marvelous metaphor he uses when he is recovering his senses after being found and brought to Cordelia's tent.
You do me wrong to take me out o' the grave:
Thou art a soul in bliss; but I am bound
Upon a wheel of fire, that mine own tears
Do scald like molten lead.
I think if you are looking at Lear based upon Aristotle's characteristics of Tragedy, you could focus upon hamartia (the tragic flaw). It is very hard to not feel sorry for someone if they are tragically flawed (which leads to their downfall).
What Shakespeare did with Lear is in keeping with Aristotle's philosophy of Tragedy; History is not as important as Tragedy, because showing what may happen as opposed to what has actually happened is more instructive. In as much as Shakespeare was not retelling an historical narrative in Lear, he was showing an Aristotelian Tragedy. See a full discussion of tragic elements at the link:
I not only like Shakespeare but also find him still contemporary. His plots and characters are universal. I never feel pity for Lear because he is a character does not believe in truthfullness. He likes flatered. In this world nobody feeds himself on others cost rather survive on own. But lear thought the youngest daughter was ignorant and she won't be able to survive on her own. Thus he mistook her assertions and faced the music. The other daughters were pretensious.
From the point of Aristotle's view, its based on co-incidence and of course you can accept the views of post#3 and #4.