I guess chess has a lot to offer: it's a game which everyone can play for very little money, nobody is discriminated for their gender, skin color or race, age, cultural or economic background, sexual orientation or religious beliefs.
It opens up a universe of ideas which can be mastered. It's a peaceful (most of the time!) struggle of the minds which offers you space for creativity, mathematical calculation, harmony of your pieces, crushing logic and even justice.
Was it not Tarrasch who said "Like music, chess has the ability to make people happy"? Hard to beat that!
..but then again, it also has the ability to make us feel really mad, particularly when we lose or make a horrible move... 
Why do you like chess? Post your answers here. I like chess because it is fun and it uses your brain. How about you?