What Are The Consequences Of Not Being Bilingual?

For most people in the United States there is little or no consequence. In the future that may change but when it does it will not be to our advantage.  If you study Economics one of the first things you will learn is about the importance of keeping "transaction costs" to a minimum.  In a nutshell this means avoiding adding unnecessary expenses to goods and services.  When it is necessary to document everything in several languages in order to complete a piece of business, you've added considerable cost.

If you get a good job & have to go overseas, you don't know how to communicate

You dont get to speak 2 languages!!!!!