The other people gave reasons why you might want to donate money on the margin. But my personal guess is that in most cases, college students in EA probably should not be donating large amounts (to them) of money, and instead invest it in either improving their own career capital, or (if they don't have good social or governmental safety nets) saving.
Almost all of your wealth as a college student is in human capital, so investing $s in ways that lets you either do direct work later or donate much more later is likely the best route to impact for your money.
To my eyes, honestly the strongest reason to donate money for most people in your position is something like "identity formation": you might consciously want to form an honest self-image as someone who cares about others and is willing to make large personal sacrifices to do so. I did this when I was younger, and I'm glad to have done so. But on the other hand, I value money now much less than I used to, and if I could send money back to my past self, I would gladly do so.
We still don't have enough money to bring everyone out of extreme poverty, even if EA spent all its money. The fact that I can still save a child's life with my donations really motivates me to help where I can.
That said, as a student, it might be worth saving until you've finished your studies, especially if you don't have a safety net to fall back on (like parents or a spouse).