This is a big problem why you can't have your dream yet... you were so focus on other people's dreams. It is either you watch them get their dreams or you help them, that is what you do, that is why you can't have your own dream.
I don't know if you are just being kind or being a martyr. Or maybe you think you're like a cat that has nine lives. It is ok for you to waste your life because you think you have a spare of it.
If someone needs a help because he is weak and cannot realize his own dream... what you do is you will help you will help him, you give any kind of help that you can give and that makes you unfocused on your own dreams. You are wasting your energy for other people. There is no more energy that is left for you. Your time has been wasted, your momentum gets stopped... the worst is the person that you help is not even serious about his own dreams, you two are just fooling yourselves.
I have an auntie that is very kind, she was very helpful and generous. One day one of my cousin who is dreaming of finishing college ask her for help. And of course because my aunt is kind and wanted to help other people... the dreaming boy got his wish, he was sent to a very good university with all expenses being shouldered by my aunt from allowance to tuition to books. Two years have passed and the boy have a lot of failing grades, 90% of his subjects were a failure. The boy is making a lot of excuses but everyone knows that he is just bumming around and not taking his study seriously. My aunt was forced to let him stop because she realized that the boy has no future, there were many chances that was given to him but he take things for granted. In the end my auntie has a lot of debt just to send that bum to the university. She is full of regrets, she too has her own dreams but she prioritize other people first and the result is she didn't achieve her own dream. This is not the only case that she helped someone, she has been fooled a lot of times by my other cousins or even her siblings... They all asked for a big help and talking about dreams but in the end those dreams never turn into reality.
Another scenario... you watched other people achieved their dreams. What do I mean by this? you become a fan of someone who is making it big. You're a big fan of celebrities, sport icons, musicians etc. Your time was wasted because you spend too much of it supporting your idol. You buy the memorabilia, you go to the concert, you buy the tickets for games. Your money was wasted for other people's dreams. You support your idol even if he doesn't need your support. Your focus was terribly on the wrong direction. And when it is time for you to leave this world... you will tell to yourself "what the fuck did I do?, your idol is not even on your side during your sickness and weakness.
So if you wanted to help other people achieve their dreams, you have to pursue your own dreams first and make it real. If you become successful then that is the time you can help other people because you have a lot of resources. You can even inspire them and tell them your own story.
Life is very short, are you going to just waste it living other people's dreams?