This morning, I just found a quite nice idea.
No one who prevents us from dreaming but ourselves.
No matter what the other says about your dream, it is you who decide what you should do next. If you think that their opinions are true then you feel depressed and take steps backward, you are free to do so. In contrast, if you are consistent and persistent enough to make your dreams come true, you are the right side to do so.
But make sure that your dreams will make yourself better and useful person to others, not just an egoistic obsession 🙂