Life outside Earth?

Is there life somewhere else besides Earth? If there were advanced civilizations, we should know about them by now. Why? Think about us. When we travel on land, every quite often someone will get into a car accident...or their car will break down, crash. Same happens with sea travel, or travel by plane. Even our own ventures into space are not immune to problems. So whats to say an advanced alien civilization wouldn't experience similar problems in their space-faring craft? However small the probability, surely an alien traveling on holiday would have taken a route close to Earth, and inevitably, one of these ships would have malfunctioned someway, leading to a fiery fireball heading straight for Earth!

So, though I would rather not believe so, we are tempted to conclude that since no such occasion has occurred, and we must admit that as pure probability says that it has a chance of happening, or should have happened already, and yet it hasn't, perhaps there is no other alien life out there, or at least no life as advanced as we are.

Don't make too much of this post. I just wanted to sound silly, since somehow it just struck me the other day that if there were tons of alien civilizations out there, try as they may to avoid letting us know about them, surely probability alone would allow the chance of their making a mistake, or having some unforeseen accident that would consequently lead to their exposing their existence to us. Preferably as scary and fiery firebally bang loud of an event as possible.