I agree, at the moment we have no way to prove these odds. Our technology isn't up to par yet. This is all about assumptions and educated guesses.
I'm excited to see the 30 meter telescope, giant magellan telescope, and the european extremely large telescope go up. I do believe with these new tools we will be able to see more through the window into space.
Hopefully these tools should help us rely less on our assumptions and give us more facts.