If you think English is enough to communicate with anybody in this world, you are sadly misinformed. Statistically, the highest spoken foreign language in the world is Chinese with 20.7%, followed by English at 6.2%. That means that 93.8% of people do not speak English. As to how beneficial learning a foreign language would be will depend upon what you want to do in life. Knowing different languages is and has always been a brownie point.