Why is it scary to grow old?

Why is it scary to grow? When i was young, I wanna grow up quickly to do the things adult can. As a young little one, I have limitations of what action I can do. My parents are the one who decides for me. So who doesn't want to grow up? When i was young, I think that growing up is easy as being free. Being free from your parents eyes, being free from the cultures, being free from the society. When i was young, i think growing up is like a ticket, a license, to do the things that i want to do. Being careless without having to worry that might someone might scold you. Excited when I started growing up as a teen. When I was a teen, I think I'm starting to reach my freedom. I can now tell my parents what I like and act what I like to do with a little worry of might getting scold. When i was a teen, my mindset in school is "Go get a good grade and pass all your subject" and everything will be okay. Now, school is the only problem. Long discussions, school projects, activities and many more. How can I be free with all of this? And then I started to doubt that growing up is freedom. But still, I pursued and conquered those doubts. I graduated at a University! Yes! Freedom! Here I come! When i was an adult, I started living on my own. Working to support myself. Being free from my parents, doing things I want to do. It's the most joyous feeling in my life. But then reality hits me hard. Bills. Relationship. Being a parent. I started getting scared to grow old. Can't do the things I used to because of limited movement because of old age. Seeing my parents dying. DEATH! I'm scared to grow old anymore. I don't wanna die. I don't want to live my daughter alone. Having thoughts of that made me worried a lot more. How come no one told me that growing old is this scary? This is not what I imagine growing old when I was young.