I think my dream is too big but I can't let go (repost)

I've had this exact dream since I was 4 years old and I'm 16 now. The problem is, that dream is really expensive and I come from a working middle class family. The second thing is, my parents don't support me. They always say I can tell them my goals but when I do, they say it's ridiculous and push me to be interested in something else. Like any other dream, this requires a lot of effort but I'm the type of person who gets tired easily and even school work is too much for me to handle. Like I said, I'm 16 so I really have to do something now but there are no opportunities and there is nothing I can sign up for since my parents don't allow me to. I know I'll have to break my beliefs and find another dream but I can't. My worst fear in life is to not be able to do it. Idk. I just need advice on how to be okay with knowing that I'll never achieve it.