>>717201000
A lot of people never read his journals and have no idea about his fucked up childhood where his abusive uncle beat him up and kept him locked in a bunker.
When he kills him and discovers his powers in the process suddenly he feels special. Then Amelie comes along and makes him feel like a chosen hero.
He was also described as a good-natured and ambitious legendary porter by the people who worked for him when his sanity was intact. It's a classic tragic downfall and Sam could have easily turned out the same way if it wasn't for the right connections that he made during his journey.
A prequel game starring Higgs could be really well done in the same way that MGS3 showed the downfall of Big Boss.