Mater eventually learns that others are laughing at him and not with him. He believed his entire life that others were laughing with him. But after he learns that he's a idiot and a fool he begins to question if he really is one and he wants to change himself. It's very heartbreaking that others are loosing faith in him, hope in him and trust in him. How could someone so innocent as Mater be laughed at and hated? He can't help be who he is. He was just born like that. It's his special cover to pretend to be an idiot but deep under that hood (if he had one) he's this genius when it comes to the bits and pieces of car parts. He later learns "Be Your Self And Don't Let Others Try To Change You, It's They Who Need To Change, Not You." so he doesn't have to change after all. He just needed to be himself the entire time and to ignore the people laughing at him. It's they who needed to change, not him.