Well when you want to comeback home , you don't want to come across a clone of yourself who already married your lover, had kids, settled down and your ex lover says "you were never around what did you expect and besides it's not like I'm cheating on you because it's a copy of you". I'd imagine time travels faster when you are out exploring deep space and having a blast while the copy of you is living his life on earth. Yeah, still worth it.