What are the odds?
Suppose I give you a bag of 1000 bronze coins which has one gold coin in it, you don’t know that, and you want to know is the fraction of gold.
You cannot look inside the bag.
You put your hand in it, take out a coin, it's a bronze coin. What is your estimate of the probability of getting a gold coin? Zero.
You take out more coins, second, third, forth, fifth coin, all bronze coins. What is your estimate of the probability of getting a gold coin? Zero again.
You keep doing this, and the 10th coin is a gold coin. What do you think is the probability of getting a gold coin now? 1/10. Which is 100x the real value.
What’s the lesson, for events with low probability, you either wildly over estimate the odds or wildly under estimate it. There is no in between.