Dreams can visualize a future that does not exist
They can also be very deceptive too. Like some dreams never come true no matter how hard you try. People live their life chasing it and wake up in 50, 60 realizing it was worst mistake. I feel dreams in moderation are good otherwise they are technically nightmare. Another thing is that if metaverse and virtual reality kicks in a lot of people can live in dream and have life they never had.
The brain likes to makes things grander and more beautiful than they truly are in terms of what we want or expect. So, most dreams are unobtainable. However, all dreams are unattainable if we don't do anything to realise them.