Have you ever had a moment where you wished you could return to a previous time in your life? You could move back to where you used to live, take up your old activities, reconnect with your old friends. The problem is that you aren't going back in time; you're always moving forward.
Even if you did move back and get your old job, you're now older than you were. You have new experiences and new knowledge. You are not the same person you once were, so it is an delusion at best.
People cannot unlearn their knowledge or unlive their lives. People trying to return to their past are seeking a safety in their memories, but ultimately, they don't live in their memories; they live in the now.