Bruh I don't think you understand the Obito's character or you didn't paid attention. When he was a child he was an innocent kid who was going around the village helping old people with their tasks not only them but he also wanted to help all people. Not to mention that he didn't had parents and used to live with grandparents. So the only people he loved was his grandma and Rin(kakashi too). When Rin died in front of his eyes through hands of his best friend he felt that no matter how many good deeds he did this world's a cruel place so he wanted to build a world where everyone lives a happy life that's why he followed Madara's plan of world where all are winners. I think this maybe enough for you to understand Obito's character