Lasik success and dying alone

When you get Lasik, you can't just look at the 98% or whatever of people with successful outcomes, you have to consider how bad it would be if you lost sight or had painful dry eye syndrome. People seem to intuitively understand weighing the good outcome against the worst outcome when it comes to their personal well being. (But they understand less why it can make sense to short the stock market, even if there's a 70% chance the stock market will go up this week, even though the logic is basically the same.)

When I visited a cave last year by myself, I brought 3 headlamps with fresh batteries, and backup batteries for all 3 lamps (in different pockets even, in case I were to lose some). A friend once said this seemed excessive, but it's *just* adequate when you consider the potential magnitude of the fail if you lost light down there (dying alone, in the dark). (I read a listing of cave related deaths a few years back, the descriptions were truly awful: man drowned alone.)