Pipe dream

[Becky]

n : a fantastic but vain hope (from fantasies induced by the opium pipe);

[Becky]

A vain dream that will never happen, given the harsh reality of life.

[Mark Zuckerberg]

Synonym for illusion.

[Donald Trump]

A dream that is so unrealistic that you would have to be smoking a crack pipe to believe it could come true.

[Tanya Shivari]

A low hope or something that is almost impossible to achieve.

[Britney]

Delusions of grandeur.

[Mark Zuckerberg]

all your hopes and dreams as a kid

[Tanya Shivari]

A strong desire that is unrealistic

[exinilu]

any of the above definitions is good. but [the following] [probably] provides an [dramatic] example of the words in use.

[Zipporah Schumaker]

an idea or plan that is impossible or very unlikely to happen: