Self-suffiency and independence
Yes, it's a big concern. There's so much to learn and do and be responsible for when you live independently that the mere thought of it is overwhelming.
I managed to move away from my family when I was 23. I took it in baby steps. I got a job at a boarding school in Switzerland for one school year. Everything there was taken care of for me (room and board, health insurance, responsibilities, etc.), the group of friends was pretty automatic (other people with the same job), and really the only thing I had to face was being away from my comfort zone. Once I got over that, I got brave enough to take it further. I moved to a new country; I enrolled online in a program to train me as an English teacher in Prague which also provided lodging and orientation once I got here. They taught me step by step how to get a job here and how to live here. I made a few friends who were going through the same process and we helped each other get established. Eventually it all became routine and I continued to become more and more independent until eventually I reached my current state of living completely on my own. Whenever I really needed help, I found that all I had to do was ask someone and they were almost always willing to help.
If you had told me 5 years ago that I'd have this independent life, I would have run and hid in the closet. I never imagined for a second that I could ever live independently or even leave that comfort zone. But the more I pushed myself and got brave and tried new, scary things, the less scary they became. It turns out it's not actually that hard, you just need someone to tell you what to do in the beginning. Find someone to guide you a bit, and you might be surprised at what you're capable of.
And the most important thing: I was miserable before. I suffered from depression and my family was emotionally abusive. I had no friends and hated my job. Now? Now I'm happy. Life is not perfect, but it is what I chose for myself. I have the job I want, the apartment I want, and plenty of friends. My boss and coworkers know about my AS and are accommodating. No one pressures me to change who I am and I am comfortable in my own skin. I can look around and think, "this is all mine. I earned all of this."
I know that not everyone is as high-functioning as me and I've been very lucky, but I sincerely believe that most people are capable of more than they realize. The only way to learn how to do these things is to take that terrifying first step and try it. If you walk on crutches your whole life, you'll never find out if your legs even work. (They probably do.) And if you find that it's too much, it's almost always possible to go back and live with your parents again, or whatever situation you're in at the moment. As long as there are people in your life who care about you, they will not let you starve in the streets.
Basically: it's NOT dangerous to go alone! Take this... advice. : )