Simple: "Anything that can go wrong, will go wrong."
Specific: "Anything with a probability greater than 0 will, given infinite time, happen."
Combine: "Anything that can go wrong can go wrong."
End Result: "Anything that can go wrong can go wrong, and so we should prepare for it."
Misconception: There is a probability greater than 0* of an Earth-Shattering Kaboom. Therefore, an Earth-Shattering Kaboom must eventually occur.
Murphy's Law is not literal in any designated set of time. "Anything that can go wrong will go wrong" does not mean "Anything that can go wrong will go wrong this week," or even, "in my lifetime." The point of the law, as I read it, is that it will go wrong eventually, and so we should prepare for it.
And really, there are so many ways we can destroy ourselves that don't include [worry of the week]. Or, for the reflective phrasing: there are so many things that could have killed us and didn't. You, the person on the other side of this screen? You are born of survivors. As are all of your line. That doesn't mean you'll be perfectly fitted to this environment--who is? Today's superawesome genes are tomorrow's killers, are yesterday's okays. But it does mean that this species is pretty darn good at adaptation. The chances of a giant wipe are low in your lifetime, and the chances of a total wipe are still small. Anything that can go wrong, will. We won't always be here. But we'll have left a mark, and all the larger of one for being able to adapt intra-generationally.
And anyway, most of that stuff isn't going to happen in any way that makes a difference to us temporal beings of limited lifespan.
* This only works, by the way, if you decide that infinite time is something currently worth contemplating, and that the probability is consistently greater than 0. As opposed to one that decreases until reaching 0.** Incidentally, then it's still not guaranteed if it not occurring also has a probability consistently greater than 0.
** As opposed to approaching 0.