Do preconceptions of NHIs put us at grave risk?

A popular theme in UFO lore is that an NHI guided human evolution, taught us all aspects of civilization, and built our greatest monuments. It strikes me that this is a potentially disastrous amount of graditude standing by. The Azteks brought ruin upon themselves by expecting Quetzalcoatl to arrive from the sea. In their excitement, they brought the Conquistadors into the very heart of their empire and the rest is history. How easily could we be deceived by a slightly more advanced opprotunist arriving from the sky? I think even our top political and military leadership could be at grave risk of deception; imagine the hoops they would have us jump through for even sprinkles of alien tech. Just a thought.