Why is the usa in afghanistan?

afghanistan is a muslim country. 99.9% of the population are muslim. they dont belive in democracy because democracy is going agaisnt their religion. and usa is forcing them to change their belive and become democratic country? usa should go to the ******* cuba or china and change their government, or go to some freaking african countries and feed the poor if they really care about people. usa is trying to steel the gold out of afghanistan just like they trie to steel the oil out of iraq. or maybe usa is just trying send as more troops as possible for iran, because iran is a big threat to usa and is a neighbor country of afghanistan. what do you think, that was my opinon and wants to hear yours. plus if we look at the history, afghanistan is the only undefeated country in the globe, its a graveyard for empires. who do u think will win