I'll jump in here with a few observations as a turner who is making it - sort of. I started my woodworking business 13 years ago. It grew out of two things. One, we needed someone to stay home with our newly born third daughter, as we could not see putting her in daycare at eight weeks old. SWMBO worked less hours, 37.5 compared to 70-80, drove less miles, 3 each way compared to 51 each way, had better benefits, made more money, and got weekends and holidays off. Two, I had the advantage of a hobby with the potential to become a business.
We struggled for a lot of years. In addition to watching the baby we pulled the two older kids out of public school because of the problems there with both teachers and students, not to mention the administration. I started schooling the kids and working "second shift" in the shop after SWMBO came home in the evening. I also worked weekends.
I am also personally acquainted with several very well known woodworkers and woodworking authors. The one thing we all have in common beyond our love for the craft is our wives have good jobs. As I travel about doing demonstrations and teaching, it brings in good income, but I tell people my wife has a good job so I can do this. I could do even more if it weren't for the kids, but they are the highest priority in our lives at the moment. Getting them a proper education and seeing them be sucessful in their chosen lifestyles has been very gratifying. As an aside I was talking with a good friend of mine today, and we were talking about the value of diversity - not the ethnic kind either. I teach, I have a successful DVD, with another about to be released, I do both art and functional turning, and I build furniture. I am doing better than a lot of my contemporaries in many disciplines who have chosen to focus on a single aspect of their craft. For example, the show circuit is way down right now, with no end of the downturn in sight. Since I do not rely on shows solely for my income, it does not affect me much.
There are a lot of people in our culture today who buy into the "must have" syndrome. There is a huge difference between what we need and what we want, and what we think we need to have is often more in line with what we want more so than what we need. I have been fortunate in that after those first few years of struggle I have been able to plow a lot of what I earn back into my business. That serves two purposes. It improves my working conditions, and it keeps the government's hands off of a lot of my money. But we work hard at not living beyond our means. That is not an easy thing to do in today's culture.
To come back to your question, it becomes more of, can you make enough to live in the manner to which you have become accustomed, or are you willing to make adjustments to that lifestyle to accomodate your chosen profession. New cars and big houses do not often go with the woodworking lifestyle, so it all depends on what you think you have to have. Ed has some very good info for you, and I can tell you from personal experience with him that you should listen very closely to what he has to say. Do the math, and then figure out if you can make it work for you. This goes for any profession/lifestyle combination. Unfortunately, too many people have the itch, but not the scratch to make it happen.
You are young and have lots of time to develop a plan, so make the best use of that time and you will do well.
Bill