Interestingly, no one has really mentioned the standard advice to a younger person: “Build because you enjoy the building process. If you don’t enjoy it, buy one already built.” Same rule applies to everyone, regardless of age. If you finish it and find you cannot fly it (health, insurance, whatever), so what? You had an enjoyable experience, can sell the plane and get your money back. Sure, a disappointment if you never fly it, but all in all, a great experience. A few years back a local repeat offender was working on his second RV when he found out he was going blind. He sold it, recovered his investment, told me he had no regrets.