This country has a lot of stupid people in it. It's basically what it comes down to. Plus there are so many different types of mixed socio-economic, ethnic and cultural backgrounds that oftentimes many people don't know their true identities (aka-they don't "belong").
As a result they feel worthless and crap like this happens. Not sure 100% if that is the case here but in most cases it is.
I really think in this case this guy was just an evil nut-job trying to make a name for himself and figured hey....huge premiere....I like the movies....this is my 15 minutes.