[dancing spawn of ungoliant]

well, Melkor cursed Húrin and his kin. i think that Narn i hin Húrin, where the story is told is very sad and i wouldn't say that Túrin was insane.
imagine: a little boy have lost his sister, mother and father before he was even ten. he had left his home and did a tough journey to Thingol and Melian. he got blaimed for Saeros's murder though he was innocent.very cheery, isn't it.
Túrin killed Beleg 'cause he thought that he was an orc(there was dark and suddenly he awaked and thought that Beleg was an enemy).
He married his sister but he didn't know that she was Nienor. He hadn't ever seen her and Glaurung-dragon had done something to Nienor so she couldn't remember who she was.

so, lots of accidents and "bad luck".