Hello,perimeter ,professor's,have you noticed that the human animal,has a problem,one that is probably keeping it from making contact with interstellar lifeforms?
For some reason ,man hates and impedes ,anything that could be a potential threat to him.
That,the aliens must already know ,and are probably waiting for our us to lose or give up,this reaction.
It all stems from human ego,but as long as we keep expressing it,by acts of war or aggression of any kind,we have not reached a workable social order,not one that would open a new way of thought.
Instead of seeing an encounter with another life form,capable of travel to earth,as an honour,we immediately would look for their weakness,try and steal from them,create propaganda ,such as aliens found in bed with rock star,and generally screw it up.
The aliens see this and know that they could never get respect without using fear,so they wait.