Why expensive/good games are fake usually?

Because people either don't read the rules or don't understand and they think they're going to be given the games. Or they're douchebags who want to troll with the latest game release.

People like to be asses in real life and even more so on the interent, sad right?

Oh well... :-/

They don't grasp the way Steamgifts giveaways work. They make the giveaways thinking they'll get the game of their choice.

Trolls, and idiots ofc...

Because people either think steam will magically create the games out of thin air and give them to the winners or they think they'll get the games. Or they're just being assholes.

Check their profile first to see if they posess a positive feedback rating if you need some assurance.

People believe it's a website about getting Steam gifts, like, you declare "I'd like to be offered Skyrim", and if someone feels like it, he will gift it to you.

Obviously these people want to be gifted the all new version of modern FPS-es or action games, since these are the kind of games that clueless people crave. (yep, I'm flaming and generalizing!)