I heard a million times that everything is possible, as I am sure you did. I have to say that I agree that everything is possible. You never know what can happen. Even the most incredible thing you can think of still has a chance to happen.
However, in my opinion, the debate is not if it’s possible or not, but if it’s probable or not. Probable shows you how high the chances are that something will happen and this is what your really care about. No one is interested if an event is possible or not if it’s probability to happen is extremely low.
You are not going to make an insurance for your house in case it gets hit by a meteor, even if it’s possible, but it’s likely that you will make one in case of floods or earthquakes if you live in an area with a high risk for such events.
Impossible is nothing but probability is what matters.