It’ll never go wasted.
Steve Jobs’, in his famous Stanford Commencement Speech told how all the calligraphy he had learned in his college after dropping out(yes, he did learn after dropping out!) helped him out later when designing the user interface for Mac.
I recently had a similar experience.
I had learned SQL in 11th and 12th grade and at that time, I thought that it was of no use. However, now its all coming back. Many people are considering DBMS in this semester as most difficult or one of most difficult subjects but I am able to easily go through it!
The lesson to take is that whatever you learn never goes wasted. It all comes back sometime!