It's never amazing that people don't realize that "open minds" are quickly filled with garbage.
Best to have a guarded mind ...
The key is to take personal responsibility for understanding.
That is very hard work.
In the case of this topic it means making the effort to understand the history.
An excellent place to start:
https://www.amazon.com/UFOs-National-Security-State-Chronology/dp/1571743170
https://www.amazon.com/UFOs-National-Security-State-1973-1991/dp/0967799511
It takes courage to have an open mind. You cannot know in advance what new knowledge is good or bad unless you consider it. That doesn't mean that you must embrace all new knowledge...it merely means you must consider/evaluate it.
A guarded mind is a fearful mind...and a closed mind is an empty mind.
BTW, you cannot fight an enemy you cannot define/know. And you cannot define/know your enemy if you are unwilling to consider what he is and what he believes.