Well we shouldn't have sympathy for Lear. He is a man more sinning than sinned against. His blindness, lack of self-awareness, wisdom and foolishness all led to the position he now finds himself in. If it wasn't for his foolish decision to hold the "love test" he'd still be in power. What is quite ironic is that the reason Lear held the love test is so he could "crawl unburdened to my death" and to "prevent future strife". The result of Lear's actions is that the opposite of his wishes occur.
Although Lear wouldn't been in such a bad position if it wasn't for the evil characters Regan, Goneril etc, who have no scruples and deliberately undermine him. Even though these characters are so evil, fundamentally it is still Lear's fault as if he hadn't spoiled them as children they would still have the respect for him that Cordelia has.
Over the course of the play Lear slowly grows in self-awareness but it is(as in all Shakespearian tragedies)too late. The only victory that can be seen in this play is if Lear finally becomes self-aware, acknowledges his faults and accepts his foolishness.
Lear in my opinion doesn't deserve any sympathy as he is the author of his own destruction, yet I cannot help but have sympathy for him when he is stripped of everything he posed, cast out to the "heath" and left to go mad. This is not a fate even the worst human being should ever have to endure.