riding 4,000 miles a year for 40 years gives you a 4.2% chance of dying in an accident
No, it doesn't give me a 4.2% risk of dying. That 4.2% (assuming your math is correct) is a figure for the entire population which doesn't say much about an individuals level of risk.
It is possible to ride in a low risk fashion that will put an individuals risk at a significantly lower rate. There is a reason my insurance rates are drastically lower than a 16 year old on a super sport.