Why does France need to speak french?

pourquoi l'angleterre dois parler anglais?

The only reason that we call the French language "French" is because the French speak it. If the language came from Libya, we would call it "Libyan". There is nothing inherent about the sounds of French that makes it belong to France. However, since it was the people of France who developed this language, it seems proper that they should speak it.