Language is a conduit for thought. It is timeless and encompasses a past and a present. Through words, we as humans express our thoughts in a way unique to our surroundings. Korean speaker will have access to different meanings than a French speaker and the French speaker from an English speaker. However, more than half of the languages spoken today are considered endangered by linguists. These are the languages from the small towns or tribes of indigenous people. They hold on to words that many of the world does not know and some will be irreplaceable.
In my personal life, my own family has speakers of an endangered language and endangered people. The art, history, religion, stories, and so much more is bound to be gone with the language. It loses its pertinence as the people stop speaking the language. My great grandmother determined the language to be superfluous knowledge in an English speaking world. In these decisions, languages fade, and unique thought patterns cannot be verbalized as easy as before.
My intention here is not to guilt the people of large language communities, nor to pressure people to learn more languages. Rather, value the languages around you and if that means learning a new language then do it. Preservation of culture may not have any meaning other than sentimental, but that is a motivation to some extent. I ask that you look at your own culture every now and again to see what the people who came before you had to say and what they thought, even if that involves a translation.