For some people, having their life planned out is something that has to happen for them. For me, it's not the biggest priority.
Yes, I have a rough sketch of what I want my life to be like, but I'm also prepared to take whatever life happens to throw at me. I'm not one of those people that can tell you at exactly what age I'll be married at, or what house I'll live in once I graduate, or even what job I'll have. I'd like to say that I know these things, but things change. Life gets in the way. Even the smallest thing can drastically change your life.
It's OK to not have your life together, it makes things more interesting. You'll never have to choose a path in life that you're not happy with, as Lewis Carroll said, "When you don't know where you're going any road will take you there."
Not having a life plan means that you have time to sit back and do the little things in life. You'll have a chance to gain more life experience. Whether that be with travel or some other thing, you'll have more freedom to go and experience it. Taking a risk isn't always a bad thing, risks will help you grow as a person
Sometimes not having a plan can be the most rewarding experience.
You don't have to be scared of the unknown.