Have you ever bounced a rubber ball on the ground? The surface area of the earth is approximately 12,478,143,744,000 square inches. So, it is trivial to deduce that the odds of a rubber ball landing in one particular square inch of the earth's surface is 1 in 12,478,143,744,000. Therefore, the odds of bouncing a rubber ball and it landing in any particular square inch of the earth's surface make the act one of nigh-incomprehensible improbability. For some perspective, the odds of winning the European lottery is 1 in 116,531,800, so every time you bounce a ball and it lands in a particular square inch of the earth's surface, you are witnessing an event that is more than 1,000 times more improbable than winning the European lottery.
So, why is it that this incredibly statistically unlikely even can occur?
Simple: it isn't
pure chance that determines where the ball falls. It is physical forces such as gravity acting on that ball, as well as the initial positioning of the ball when it is dropped.
Point is, it's trivial to render almost
any single event as being statistically improbable if the only thing your calculation takes account of is things occurring randomly. But we live in a Universe where things exist in certain states which make them susceptible to physical laws, and these laws alter the interactions of things in ways that these simple probability-based calculations simply fail to take account of. Nothing exists in a total vacuum such that the only factor that can influence its outcome is "random chance".
This is part of a field of physics known as statistical mechanics (
https://en.wikipedia.org/wiki/Statistical_mechanics). It's something I barely understand myself, but I'm sure some people more well-versed in physics will be happy to explain it in more detail if needs be. The thing to take away from this is that so-called "probability calculations" for phenomenon like the Universe or the Earth forming are completely meaningless, since you can apply the exact same logic to almost any formation of matter and deduce that anything is statistically improbable if the only factor your equation takes account of is pure, blind chance. It's a simple, false dichotomy.