For the crack in perception to occur a person must be open to new experience; perceptive; and discontent.

Many people are for lack of a better term, “full.” They know what they know well whether that be intellectual expertise or vegging in a basement playing video games. It takes some humility to get how far we are from knowing it all.

Also most people see what they expect to see or are sugested to see. Anyone who has tried to get accurate eyewitness reports knows how hard that is and how quickly people together coalesce on a shared view right or wrong. So two things; the ability to see differences accurately and to hold on to that observation against opposition.

Lastly people are taught that they should be content with what is (or appears to be, really.) Despite irritants or challenges, if someone is busy working out those towards some goal they’re not interested in why.

IMO only if someone is thus restless in life, stubbornly perceptive, and also aware that there’s more to be known does the opportunity present itself — and even then there’s a decision to follow that thought scary though it be.