When you start off with UFOs you're probably not going to get a lot of buyers.
If UFOs do exist then obviously any alien species that has figured out how to travel among solar systems and possibly galaxies would be way more technologically advanced than we are and could wipe out mankind in a heartbeat in they so chose.
Think about it. If they could harness enough energy to freely travel in space then they could harness enough energy to seriously mess with mankind.
Good points. But I must say, I personally go back and forth on whether or not life is out there. I find it hard to believe that we are it. Out of the vastness of space, there has got to be other life, somewhere.
But, I agree with your above post. The ability to travel here would be a bit of a hiccup.