That's incorrect. Economics is not a zero sum game; in fact the better others do, the better off you are: You are much better off running a business, working, or just living unemployed in a neighborhood, city, country, or world full of wealthy, free people than you are where the others are poor and oppressed.

And that's only if you are a completely selfish sociopath and care nothing for the welfare of others. If you are a healthy person who does care about others (which is a foundation of democracy - the belief that others should get a vote equal to your own), all the more reason for them to be free and prosperous too.

U.S. foreign policy has long supported the freedom and prosperity of others, in large part for that reason. (Yes, there are many exceptions to that policy; I'm just talking about economics. EDIT: And yes, there are many exceptions to the economic policy too.)