In most interactions, you're capable of winning. If you push hard enough, kick someone in the shins, throw a tantrum, cheat a little bit, putting it all at stake, you might very well get your way.
But often, this sort of winning is actually losing.
That's because we rarely have an interaction only once, and we often engage with people we know, where reputation and connection are at stake.
Culture, it turns out, is built on people losing in the short run on behalf of the long-term win. Connection and trust and reputation are worth more than any single inning.
Not to mention that a tantrum not only ruins the relationship, it can ruin your day as well.