Yes, see: Fermi paradox.
How does that work? You are justifying your belief in aliens based on a paradox about how we can't see any and totally should if they existed. At least if aliens were anything like us in the way they developed.
certainly they exist. But I believe that the governments of the countries know a lot about them, but they are hiding it from us. It is possible that they even contact
Possible. But then the aliens wouldn't be very interested in making sure the population knows about them. Because if they were the governments wouldn't be able to stop them. Especially if it was aliens with spaceships and not only a distant message of some kind.