I was heavily encouraged to go to university after school but had no real ambition or direction. I decided to study biology because it was one of the few subjects I enjoyed in school but quickly fell behind, failed all my courses, and dropped out after a semester.
>>11486 has the right advice, working menial jobs for 5 years was really useful. I think a sense of pointlessness and depression is just endemic to who I am because I've never been able to shake it but at least now I have the maturity to sustain full time study in something useful.
Don't feel like a failure, it's just part of growing up. Spend the next couple of years figuring out what it is you want to do if you need to, just try not to waste it. My main regret is simply not going back sooner or using my time to have more interesting experiences. Still, it's good to know that it's never too late; I know a chick who quit her job as a pharmacist to study CS because she was bored of her career. There's no shame in being in education when you're older, not everyone follows the same trajectory in life.