These kinds of risk calculations are perhaps useful for insurance companies, but for individuals doing a &quot;dangerous&quot; sports there is more to the risk than merely probability.<p>In particular, with something like cave diving and mountain climbing the &quot;bad&quot; outcome is going to be death of the individual or their friends and it will likely be the result of a series of bad decisions under stress (each of which makes the situation more dire) rather than an exceedingly rare multiple systems failure.