The wealthy are not always the smartest. You can inherit wealth. As for the smartest and most powerful, the world does in general terms belong to them anyway.
Being in power doesn't automatically make you intelligent on all levels. President Bush I believe had street smarts. One particular election may well have been rigged so that he won office. He diverted attention from his stock market activities that were dodgy though not illegal at the time via getting the USA and other countries involved in Iraq. His IQ however was considered fairly low compared to other presidents. Obama is more book smart than street savvy and that is the reason he won't stay president.
There are those in the world capable of inspiring others, through religion, to do the most horrible things. What is happening in Iraq right now has to do with this sort of power.
So does the world belong to those who can grab power and hold onto it? Well, there are democratic checks and balances in countries such as the USA, the UK, Australia, Canada, and New Zealand. And so there are limits to just how much power one person can have in such countries. As for countries that don't have a democratic system, well, the results for the people can be disastrous. North Korea is a great example of this. There you have people starving and a showcase supermarket with all sorts of goodies the average person in that country can't afford to buy. This supermarket is really only on show to foreigners to give the impression that North Korea is progressive. It in fact does the opposite.
When the American colonies broke away from the British Empire it was under the premise that there should be no taxation without representation.
Australia became a federation in 1901 with the idea that there would be state premiers representing the people of the now states which were the colonies. Even the Northern Territory is represented. There is voting. In 1902 women gained the vote in federal elections. Thus the people may not directly have the power but they do have an indirect say in who has it and for how long.