Why do so many Americans believe in imperialism?

I personally think the Military should be gutted. it is too large and it has never shrunk like it was supposed to after the Cold War ended, there is no need to have 12 Aircraft Carriers. we are the only country that has Aircraft Carriers because they are too expensive to operate. so other countries don't even bother with them, Americans are brainwashed that they need a Super large expensive Military to survive, they do not, we had no military to speak of when wars ended, ever since World War 2 Our Military has been out of control