Hey OnlyOneLife,
I'm also 18, and if there is one thing I've learned it is that you need to decide for yourself. Others advice won't really help you until you've actually experienced it, so make a decision and go after it. The worst that will happen is you'll end up having to get a job (which many people are recommending from the outset).
I'm going to University and running a medium sized personal development website (
Scott H Young ). I'm currently just using AdSense, but I'm releasing my first book for sale in the fall. I'm not getting a job as a career, but I will be working until I can live off my business.
My reasons for going to University isn't because it is a great educational opportunity (real life is better if you don't just want a piece of paper) or even really for "life experience" (pretty vague benefits for a lot of money). I'm going to University because it will be a great opportunity to learn and meet other people, and my first year has been just that.
Getting a job is a lot easier than earning income on your own through a business, don't let anyone tell you otherwise. Eventually a business might pay more, but you'll have to spend a lot of time scrapping to learn how to be successful before you can get rich. Steve spent a few years of incredibly hard work before he made his computer games business work, the rapid success of his personal development business is built off of more than a decade of business, writing and web experience so don't pretend you can duplicate it nearly as fast.
If you think your age is a limitation, check out Ben Casnocha (
Ben Casnocha: The Blog ). He started his first company at 14 and now has someone else run it for him at the age of 18. Use what you have, be prepared to work and decide for yourself.
-Scott