Anyone doing that much snapping would sustain an overuse injury to the tendons. Also the cushion-like cartilage inside the joint would break down over time, leading to bone rubbing on bone. Actually I would expect it wouldn't take long. Symptoms of arthritis can be crippling, I have seen quite a few massage therapists (one of) - my own occupations - quit the industry. You could clap your hands and change the name to clap club, that would be a safer option if you are going to sustain that many decisions over the course of a day.