Because calculators do arithmetic, not maths. The same fallacies apply to AI. Language is subtly used for communication between humans.
More importantly languages are interesting !
I am back to working on my Finnish now and the grammar and sentences are fascinating !
A "thing" has value outside of its monetary commoditization.
And if you really need a reason, there's growing evidence that bilingualism can help ward off neurocognitive disorders in one's old age.