A better question is why shouldn't it? We all like to think that hard work equals success. For those without success, they want to believe this because that means that they can be successful simply by working hard. For those with success, they want to believe this because it means that they earned and deserve their disproportionate wealth.

Nobody wants to think that success is due to luck. For the wealthy, that means that they are not as great as they think they are (damages ego), and for the poor, that means that there is no sure way to become wealthy.

Of course reality is a bit more complex, hard work can lead to wealth, but it's not a guarantee. Luck factors into everything in varying amounts. Aside from extreme cases like this, luck comes into play in terms of where you were born, who you met and became friends with, or even when you live or whether or not you were first to some arbitrary line.

To me, all of this means that people should be a hell of a lot more humble and realistic than they are. I get the impression that the author of Flappy Bird might realize this, so props to him.