He has been very vocal about a "US-first", isolationist policy. You can't be the leader of the free world by saying "I only care about my country" and expect others to follow you.
The logical assumption is that the US President is not in fact a leader of anything outside of the US and only the pride and arrogance of the citizenry would lead to that title. Alternatively, it could be true that the US President is indeed the dictator of the rest of the world, but then it would be more fitting to call him a dictator rather than some Americanized version of "Great Leader".
There's no evidence of that. The President is a citizen figurehead (with limited powers) which has to fight a monumentally massive bureaucracy made up of other branches and citizens. Trump is not a godhead or even going to be considered important in the long run (a generation+). Curb the sensationalism.