I don't have money for maintaining a car. Thanks to being a twenty-year old and newly licensed, insurance companies won't touch me with a ten-foot pole. Also, I live in a city where cycling's more convenient than a car. I don't need to find parking and get permits - I can just ride to the buildings I need to go to. Plus it gives me a convenient excuse to take fun detours that may or may not end with me getting very dehydrated.