You've probably heard this tired and tiresome joke: "What do you call someone who speaks three languages? Trilingual. Two languages? Bilingual. One language? American." It seems to be a popular joke among Americans who speak more than one language, and the joke and its telling reek of moral superiority and superciliousness. Those who tell that joke see knowing more than one language as inherently admirable or denoting a higher level of civilization and sophistication.
Do these smug multilinguals, these language geeks, ascribe the same superiority to those who know two or three computer programming languages instead of just one? Or multiple computer operating systems instead of just one? Of course not. They see those as tools and understand that some people may need to be familiar with many of them, while others may only need to know one - or none.
Many language geeks don't seem to understand that what is to them a source of intellectual pleasure and satisfaction, languages and learning and using them, is to most other people a tool. Some people need familiarity with more than one of those tools. Many do not. In America, most do not.
Considering it only from the point of view of pragmatism, who needs to know languages other than their own? People who live near the border of another country or, which is much the same thing, people who live in small countries. People who deal regularly, socially or professionally, with native speakers of another language, orally or in writing. People who travel frequently to other countries. English is the native language of 82% of Americans, and for the majority of those Americans, none of those special situations applies.
Certainly, for many of those native English speakers, it would be convenient to be able to speak a second language reasonably well. But for most people who weren't exposed to other languages before puberty, learning a second language is no trivial matter. For some, it's virtually impossible. They're not lazy. They're not morally inferior. They simply can't do it. For others, it's doable, but the effort and time required are enormous and far out of proportion to the benefits gained.
Nor is the task pleasurable for many people. For them, learning a second language is unrelenting drudgery and an almost pointless grind. (By the way, this points up the absurdity of requiring passing grades in a second language for college graduation.) I've studied a few languages in my life (Hebrew, Afrikaans, Latin, Russian, German, Spanish, and French) and reached varying levels of reading or speaking proficiency in them. I've long forgotten most of what I learned, but I remember that, while I enjoyed the proficiency I achieved, the process of acquiring it was never enjoyable. If foreign-language fluency were available in pill form, I'd happily swallow those pills, but I have no intention of studying a foreign language again. For me, foreign-language study was always dreary and dreaded.
My wife is the opposite. She's quadrilingual (English, German, Spanish, French), works as a language tutor and translator, and reads foreign grammar books for relaxation. She has a network of friends who are of the same bent. Her abilities amaze me and her choice of reading bewilders me. She feels the same about my technical orientation. My mathematical and scientific knowledge and my computer abilities are modest by my standards but seem magical to her. It's all a matter of how one's brain tends to bend.
I've heard the argument that you should learn foreign languages in order to be able to read the great literature of other countries in the original versions. That's nonsense. How many people can become fluent enough, at a high enough level, in even one foreign language to be able to read the greatest works of literature in that language? Consider, too, how languages change over time, so you'd have to achieve a very impressive level of fluency to be able to read the great works written in a foreign language in different eras. And that's just one foreign language. For all but the tiny minority of people who have extraordinary language-learning abilities and extraordinary amounts of time to spend at it, it makes far more sense to read great works of literature in the best available English translations.
Let's briefly address a peripheral issue. Language geeks who sneer at monolingual Americans also like to compare them unfavorably to citizens of other countries - usually (Continental) Europeans - who are said to generally speak one or more languages in addition to their native one. That's often true, for the pragmatic reasons I mentioned above, but it's also often true that they don't speak those other languages well. When Americans do study other languages seriously, they tend to work extremely hard at the grammar and spelling - and also at the pronunciation. Europeans tend to be cavalier about English, and especially about pronunciation. This can even apply to immigrants who've lived in the U.S. for decades.
If you enjoy learning other languages, then good for you. Knock yourself out. Learn as many of them as you want to and have time for. Just remember that a second language is a tool, and the monolingual majority around you has no need of it or interest in it.