I think it's very important to have a plan B, as well as thinking about a safer, reasonable way of realising your dreams. Let me tell you my story, because I think it's directly relevant to all this.
A year or two ago, I wanted to become an academic philosopher. I was doing my Master's, thinking that I was working towards my dream. What I eventually found was that what it means to have a job as a philosopher was very different from being a philosophy student/enthusiast. I liked to think of ideas and talk about them in a friendly environment -- that's what I fell in love with as an undergrad (I would get major Ne highs and chills running down my back), and what I enjoyed as a tutor. It was the social bit of philosophy I adored -- a safe haven where insightful concepts could be shared -- an ENFP's dream. As an academic however, I would spend the vast majority of my job by myself -- struggling with the same few pages endlessly and writing my own shit well into the night. Therefore my dream of being a philosopher, the elements in philosophy I enjoyed, did not actually align with what the job of being a philosopher mostly required. See the difference? Now I know that academia's not for me, and really wished I would've taken more practical papers like economics, law, and statistics, so I could package them together with my philosophy degree to get a public policy job. I'm going back to school next semester to do a graduate diploma in stats. So as difficult as it may be, you have to ask yourself, Is this really my dream? Is this really what I want to do as a career? And what if I'm wrong?
My dream now is to be a great writer, and to become that creative person I always wished to be. Here's the important bit though -- I'm not just going to drop everything, maybe get a degree in English, and do nothing but write. That's not a realistic way of sustaining the dream. Instead, I'm going to try and find a career which I still enjoy, one where I could go out see things, learn how the world works more, be financially secure, and still have time for my own projects (which in New Zealand, isn't hard. Most people work reasonable hours and still have the weekends to themselves). All of those things will still help me as a writer, directly or indirectly. Right now, the plan is to get involved with policy, but hey, if I get a chance to become, say, the editor of a magazine, or to help run a community project promoting kids to be creative, I'd consider those too. Neil Gaiman -- one of the greatest authors in our time imo -- said his dream was always to make a creative career using his words, but the road to that dream was a marathon not a sprint. Your dream's like a distant mountain that you want to get to, and as long as the things in your life are taking you closer to that mountain, you're in good shape. Shoot for your dreams, but be thoughtful, be patient, and figure out the best way of getting there.