Of course, not because it's great and makes you a better person, but mainly because it makes other people feel good. Imagine a situation when you needed something but you did not have. Something that played an essential part in your life. I know many people did not have a chance to go to a better school because they did not have money for that. So why not giving them a hand and help realizing their dreams? Another example, when someone needs money to finance his/her kid's healthcare. Even $10 or $15 can be a big assistance for them. So why not to do that when we have the means?
I remember my friend's sister had cancer few years ago, so all of us dedicated some time out of studies to go to the streets and ask for sponsorship from random organizations and companies. We managed to collect all the money and financed the surgery and medication for her. If we were to act alone, it would not work, but all of the small efforts combined made a difference. The same with charity, you can donate even $1 (very small amount of money), but it will make a big difference!
So I will use this space and encourage people to do that, because it pays back quite often!