The US is not an empire. 
The US is not like Rome specifically. It tries to excert political influence in those areas it considers to be of national interest. Being a huge country with needs of lots of resources and markets, and having a powerful military makes it do that on a global scale, like any other country in the past who was in a similar situation.
The Roman empire got destroyed because of a combination of many things. Expansion to barbarian lands and unjust treatment of them was not one of them. It was rather the other way around. The barbarians came to Rome

The US is not like Rome specifically. It tries to excert political influence in those areas it considers to be of national interest. Being a huge country with needs of lots of resources and markets, and having a powerful military makes it do that on a global scale, like any other country in the past who was in a similar situation.
The Roman empire got destroyed because of a combination of many things. Expansion to barbarian lands and unjust treatment of them was not one of them. It was rather the other way around. The barbarians came to Rome

Cetero censeo religionem delendam esse