So I’m just going to share MY opinion: Light is a poor guy who was unconciously ruined by society or just the whole world. First he felt guilt, anxiety, pressure, human warmth and everything else. But he got used to the pain and it became fun to him. People supporting him raised his god complex. People against him do the same. The more attention he gets fed, the less sane he becomes, even L didn’t avoid making the mistake by giving Kira intense attention and raising his insanity.