好高鹜远
Hitch one' s wagon to a star.
Gace at the moon and fall into the gutter.
Vaulting ambition that overleaps itself.

eg：You must not hitch your wagon to a star when you make your plan for your future.

同义词：想人非非 To be in the clouds.
反义词：脚踏实地 Come down to bedrock.