During this 15 year break, I could easily notch away at the big circle of knowledge, generate side income, write books/tutorials and contribute to companies/individuals in software aspects.
I would also be able to work at night. I have a reversed circadian rhythm. I spend most of my nights getting 2-4 hours of sleep and murmuring about math and programming during the other 4-6 hours. A typical job schedule holds back my productivity.
My happiness is defined by obtaining/spreading knowledge. 40,000 (post-tax) a year is more than enough to maintain a household of three, take vacations, and stay on top of technology.