I think that's what makes Negan an interesting character, though. He truly believes that his actions are justified because he's rebuilding civilization, and he believes in certain standards that need to be upheld, while not being able to recognize how his abuse his power and sadism are also ruining what he's trying to accomplish.
He claims to only kill was a means of controlling people through fear, and he enforces a "kill as few people as you can" rule with his underlings, but he clearly enjoys killing. He strictly enforces a "no rape" rule, but he has multiple wives that are arguably forced into a relationship with him because of the power dynamics of their society. He's deeply fucked, but he's also managed to get results and create one of the most well organized, well protected societies we see on TWD. In a lot of ways his goals are the same as Rick's, which makes him a little more interesting than some tactlessly brutal nutjob like the Governor.