Why is it such a problem that i don't drink?

So i am 21 yrs old and i don't drink. A lot of people are very surprised when they find this out and they also seem to be condescending about it to. Why do they feel they can imply that i have no life because i don't get stupidly drunk and then make a jack of myself. Its my choice. I had one persona at a party ask me why i would even come to a party if i wasn't gonna drink. I dunno maybe to hang out with people?! I feel like if you need alcohol to have a good time, then maybe you should prioritize your life