I am a 21-year-old undergrad student in a public university. A little old for freshman actually. After high school study, I spent one year in lab, and another year trying to start up sth. As I don't achieve any significant thing that can insure the rest of my life, then I said, go to United States and try some luck. But after the half year study, I didn't see any purpose of the college life.
I have learned basic math skills such as differential equations and linear algebra in high school. I self-taught algorithms and c/c++. I am an active contributor to opensource community. Recent two years, I mastered several scripting languages (js, php, python etc.) to accomplish a web project. Especially in computer vision area, I have many experiences. When I participate icpc contest, I saw what 4-year student done. That scared me. They don't have basic programming instinct.
Indeed, a diploma can make life much easier by getting a job in Microsoft or Google and my college's rank is not that bad at all (around 20+). But I don't want to spent so much money in next 3.5 year and gain nothing. Besides, getting a job in big company and establishing own career after 30+ seems not so interesting to me.