Why is the president of the US referred to as the most powerful person in the free world?

because people forget its the rich and wall street & associates that actually control things, look at the donors for both campaign party's and you will see, some are people you have never even heard of. 

Yeah, really. Nukes? GDP? All free world leaders need to have an arm wrestling contest to determine whether this is true.

They've got the keys to the nuclear football - so...