At what age does it become unacceptable for a child to be a "bad loser"?

[Caligula]

DS is almost 7 and is incapable of playing a game like football or rounders or any other competitive team game without it ending in tears, wailing and breastbeating if he's not on the winning team. Even if he personally scores a goal or does well, he'll be OTT traumatised to be on the losing side and will continue to sob about it for half an hour. Same with individual games come to think of it - he can't stand losing. When I go to pick him up from his club, he'll be crying if he's lost a game.

Up to now I've ignored it and jollied him along, but I wonder if people think he's a brat and should by now have developed a stiff upper lip and know how to lose more gracefully. Should I attempt to get him to be more moderate in his reaction to losing? And if so, how?

Interesting point about pretending Nightynight.

I suppose it depends on how important you want him to think scoring a goal is. The balance between doing your best for yourself and your team, not letting other team-mates down, and recognising that it actually doesn't matter in the great scheme of things whether they win or not, is such a delicate one...