Having access to the untapped resources of a new continent, basically. Also, managing not to fragment, and never having to worry about external aggressors.
Many of the countries you disparage have BEEN superpowers at various times in the last 6,000 years. Egypt, Persia, Rome, the Arabs, the Mongols, Spain, France, Britain and Russia are just some of those who've had their time in the sun.
Superpowers are ephemeral. All those who rise must eventually fall. The USA is superpower NOW. How long will it remain so? Only time will tell. But fall it most certainly will - it's a historical inevitability.
Of course, this begs the question of who will be the next superpower to arise. This is something about which one can only speculate, but it seems likely that we're headed for a new TYPE of superpower - one that can no longer be defined in simple geographical terms. If you were to ask me who is most likely to be THE superpower a hundred years from now - my guess would be Microsoft.