"Ignorance is a symptom of the desire to avoid responsibility."
We learn from a very young age that the best way to avoid responsibility is to avoid knowledge. How many times has someone said, "I didn't know anything about it" to avoid being held accountable for the fallout of their actions. You may remember Sergeant Schultz from the television series Hogans Hero's who frequently said, "I know nothing!" to avoid getting in trouble for the antics of Colonel Hogan.
Today, much of the population has heard about the tremendous issues and corruption we all face, but so many prefer to "let someone else deal with it." They simply don't want to know about it. This avoidance of knowledge is called "willful ignorance" and is one of the dark, selfish parts we all should face, and overcome.
When confronted with knowledge they don't want, the willfully ignorant may become angry and may ridicule the messenger. They know, usually subconsciously, that knowledge implies responsibility and responsibility requires action, and if proper action is not taken, then the willfully ignorant face the ridicule or rejection of their peers, and this prospect causes them fear. Their natural reaction to this fear is anger. Those who have a more reactive conscience will tend to discredit the messenger so as to make themselves feel justified for not "believing" the knowledge the messenger brings. This is often seen when relationships fail. The participants discredit or devalue each other to convince themselves that they are not losing anything of value.
When confronted with knowledge they don't want, the reaction of the willfully ignorant is often identical to their reaction when told they must do something they don't want to do. Since people understand (usually subconsciously) that knowledge implies responsibility implies action, then the acquisition of knowledge is the same as telling someone to do something. If a person does not like being told what to do, then they generally don't like to acquire knowledge that requires them to do things.
In summary, people remain willfully ignorant for 2 primary reasons:
(1) because they fear the humility or rejection they may face by their peers if they fail to act responsibility, or, more often
(2) because they simply don't want to spend their time doing things they don't enjoy doing.
In the end, willful ignorance is a result of either fear or selfishness or some combination of both.