Stress and college - why are we doing this to ourselves again?

Today, my friends were having a conversation about school:

"I miss the routine of going to work.  Like - leaving in the morning and coming back home right after."

"Yea, I understand what you mean.  It feels like we have 15 or 16 hour days when we are here."

I had never thought about it until recently, but what is really the reason for us to be having 15 to 16 hour days?  What exactly are we trying to accomplish by being involved on planning events for our club or by staying up until 1am in the library only to go back to our rooms and try to finish more homework?

What about all-night study marathons or spending hours organizing programming for different organizations will be applicable to our daily lives after college?  How does taking a test help me become a great writer?  How do these things make us a strong candidate for high-paying jobs?

These are questions that I might find out later or never find out.  I just struggle with the fact that I am burnt out from my 15-hour days and unable to enjoy my life for the small cost of $50,000.