Dreams, just like ideas, have three possible outcome.
Outcome number one. They die. You had a dream, you believed in it for a while, you do not believe in it anymore, it dies. That is what happens to most dreams. Goodbye.
Outcome number two. You keep them out. You think about them. You perfect them. When you get a piece of them, you push them further by fantasizing on an even more perfect version of them. You alienate them from the world around. You make them a central focus of your inner life and emotions without internalizing them. They get to serve a sort of function, like the carrot for the donkey: they give you purpose, and they are also the primary reason why you are often unsatisfied and sad.
Outcome number three. You bring them to your world. And it is not mainly a matter of sharing them (though you might, you should). It is mainly you adjusting them, making them grow with you (and with your world), shrinking and expanding them depending on circumstances and people, using them as a lens through which you look at your current reality. Doing this effectively basically means that you will end up living a life in which each step you take is part of the dream, because the dream is more of a purpose, it is a frame for each one of your efforts.
Dreams, just like ideas, are great starters, they boost motivation and keep the morale high for a while. What happens with them though depends on you.