sailing is cheap... by the standards of living on land. But as you pointed out, the cost of sailing is still more than can easily be generated from the boat. The demands it put on you make creating the income are alot greater than the discount in living you get.
Stay in school. Find something you can do at a distance, or better yet, invest in income reality. (rental homes etc) and then go sailing. Or work at ports where you can find it, and spend your life on the hook and out of the harbors, eating fish, rice, and raman.