It's a cultural thing, definitely. Some Americans take it too far, but even those who don't (many), who don't think everything in life is about winning a competition, still interpret most things as competitions even if they aren't officially so. We've got tons of sayings that subconsciously make us a winners-only culture: "Winners don't do drugs", "Quitters never win", etc.

As a teenager I was totally disillusioned with it, so I mistakenly thought winning of any form and encouraging others to try to win made you an intellectually bankrupt tool. Probably made me happier, but had the adverse effect that I feel a lot lazier than other people I know because I'm more prepared to do "good enough" rather than try to outperform my peers. Being American-born, I feel like I could be seen as a poor performer by my superiors simply because I'm not doing better than my peers.