It would be a bold claim if the expected value for the number of intelligent species bearing planets in the universe would be 1.
You're still failing to understand the difference between certainty and probability. Yet you can't prove intelligent life outside of earth exists, you only keep repeating how likely that probably is, probability alone does not prove anything, try taking a medication that works in 95% but there's 5% chance of death, probability in that case doesn't sound so appealing right? That's because probability alone is not always correct, that's why scientist don't just bring probability to prove their points.
Saying something like "I believe there's intelligent life out there" it's plausible, but one can't say "I know for certain it exists", simply because you can't prove it.
And there's no such things "disproving life exists in mars" or anywhere else, that's a fallacy, in philosophy that's called "shifting the burden of proof". It's the same as if I told you that you can't prove there no flying invisible unicorns (odorless and silent), and you can't prove that, but that doesn't mean they exist.
That's why I used the word "certainty" in my original post, not "probability".