How likely is it that we are the only living planet in the Universe?

It is probably not likely that Earth is the only habitable planet in the entire universe. This is because the universe is so huge and it is possible that there may be at least thousands of planets for habitat if not millions. Though this is only a guess and the habitable planets could actually be in millions.

However, they are so stretched out in distance from earth that it seems unlikely to us that there are other creatures existing in the universe. Nevertheless, coming back to the question, it is not likely that earth is the only planet hosting life in the universe.