I’d also suggest that the public association of UFOs with “alien life forms from outer space” — fed by generations of fictional books and movies —didn’t do the subject any favors.
On top of that, when the government engages in a campaign the goal of which is the obfuscation of a subject, it encourages conspiracy theories.
In other words, it is natural to use one's imagination (unless you don't have one).
That’s part of it, but I think it runs much deeper, every religion that I can think of that worships a supreme being like God, Jesus Christ, Allah, etc. have been taught since their inception that God created the heavens and earth and suddenly waking up to the idea of intelligent life somewhere else in the world could destroy all their religious tenants.
From my perspective, suddenly evidence of alien life forms visiting earth would do nothing but enhance my idea of God and Jesus Chris as being Supreme Beings, I couldn’t explain any other reason how and why some life form perhaps millions of years more advanced than earth was decided to visit and reveal themselves.
IMO, whatever happened on Earth to create life has to have been replicated millions of times around our universe, to me it’s impossible to not beleive in alien life somewhere, has it discovered Earth and decided to visit here I have no idea.