Well how would an "investment" in dollars done in that time period, by stuffing them under a mattress? Currency values rise and fall, saying that gold didn't go gangbusters historically doesn't mean it's not money...

Your grocers income provides taxes that benefit your community and provides for employment of those in your community, who then spend their money in your community, etc. Not so money sent to China, since - by assumption of the imbalance - do not spend that money in a way that benefits your community.