The probability of dying on a bombing trip to Germany (or of dying in any 'event' involving aeroplanes) is a simple calculation once you've defined the variables.
Probability does not vary with the number of times you expose yourself to the likelihood of an event, assuming the variables inherent in that exposure remain constant. So, you were no more likely to encounter an 88mm shell on your last trip than you were on your first, unless your first trip was to somewhere defended by myopic old men with Mausers and your last took you directly over a flak tower in Berlin.
Leon's 0.9 probability of collecting his pension is quite acceptable for a motivated individual. Should it decrease to around 0.5, most individuals - even young Leon - would likely be putting the pins in their seats and moving on to a day job with Tesco's.