This isn't even a matter of philosophy, but a fairly basic mathematical premise relating to probability. It's a premise that on the whole has little direct baring on our utilisation or the meaning of the probability of an event; but one that is necessary for our understanding of likelihood.
Put simply: No matter how remote the chance of an event, it is inevitable given sufficient opportunity.
Most occurrences have a finite window of opportunity in which to happen, and there absolute chance of happening can be calculated. However, the failure of a hard drive in your computer can happen at any time, the more you use that computer the closer you come to certainty.
Forethought can turn that certainly into an inconvenience rather than a disaster.