Obito's actions and choices are understandable. Even though they were wrong you can't completely blame him. Obito is Naruto, except Naruto had the will to never give in. Plus, Uchiha have the Curse of Hatred
"A smile doesn't always mean a person is happy, sometimes.it simply means they are strong enough to face their problems." Jiraiya, Yahiko, and Itachi died qith a smile because they did what they could to help others!