I also wonder on this question back when I was in College. Of course many of us will agree that out of Centillions of planet, other life forms must be living out there somewhere. But why until now we still did not discover any life forms?
It's better that the whole truth about this must not be revealed to the public because of our current state of mind.
"We are alone in the universe" because of our state of mind. Lack of Wisdom.
-no matter how technologically advances that NASA will launch in space, they will never find what they're truly looking for. Yes, even looking and sending signals for countless of planets, no one will show up or response to us.
Do not believe on what you have seen on movies, documentary and tv series.
They will never harm us. They Love us!
They know the Laws!