You think that, but in reality you'll later realize that when you're 18, you're basically an idiot emotionally compared to four years later. And then later, you'll look back on your 22 year old self when you're 26, and think the same damn thing. The time allows for some emotional maturity to develop, and you'll be hard-pressed to find anyone that says they didn't greatly emotionally mature over the time spent in college and beyond. You don't want to go into medical school as someone whose emotional maturity is behind the curve in medical school, because there really isn't much time for it to develop once you're there. Or in residency. Or fellowship So you'll pop out at the age of 30 as a cardiologist with the emotional maturity of a 20 year old, which is embarrassing (and something I've witnessed in a few physicians in the past that spent too much time on getting to their goals and not enough time on developing themselves).