Cytat: terri
engee, love, now I know you're just kidding me:-)
This'll teach you a lesson, hopefully :D
People's behaving as if they were the most important in the world makes me feel sad about them.
People behaving as if they were the most important in the world makes me really sad about them.
The difference - apart from that little adverb 'really' - is that the first one can be perceived as slightly more formal, whereas the other as slightly informal. Nothing to worry about, as you get the meaning of the sentence anyway.