Exactly, we say '꿈도 야무지다’. As one of Korean idioms, it means his/her dream/wish is so big and looks impossibile to come true.

- 꿈도 (참) 야무지다 => Your dream so big/ambitiously / You really are serious with your dreams/plans. 야무지다 describes the ambitious and determined attitude of someone planning something. It may be said in good and bad sense . It could mean that the person dreams big and is determined to realize it. If they're too impractical and fanciful, we would probably use a different expression, like 꿈 꺠라 (Stop daydreaming). Examples: - 스물다섯까지 석사 학위 받고 그 다음 해에 결혼한다고? 꿈도 참 야무지다. = Get the Master's by twenty-five and get married the next year? You really are a dreamer. - 네 작품들을 인터넷에서 파는 사이트를 만든다고? 야, 너 꿈도 야무지게 꾼다. => You're going to create a website to sell your works? Wow, you're such an ambitious planner.