Because they say the knowledge of the whole universe is written in sanskrit in the vedas. Thousands of years the Indian sages researched about almost every topic and wrote this vedas. We would have been many years ahead if we could decode those teachings. Many lost, many still to be decoded. If people learn sanskrit, maybe someone will find its life purpose in this and do a big research on the old knowledge. Just saying. Anything is possible. knowledge is never in vain.