Good point. Mankind is not ready yet for the discovery. If we can discover alien intelligence, then it disrupts the beliefs of most of mankind.
How hard was it to accept the "Round" Earth discovery, even after Pythagoras proved it? 2000 years later, people were still being burned at the stake for believing the earth was not flat.
RE: We are not alone. The Universe is teeming with life, much of it far more intelligent and advanced than mankind