There are none so blind as those who will not see.
~ Origin unsure, but made popular by commentator Matthew Henry
It is not clear exactly where this comes from, but it has various forms by various people. Jonathan Swift considered it a cliche, so it was obviously well known in his day. According to Quote/Counterquote in “None so blind as those that will not see“:
Contrary to common belief, this is not a quote from the Bible. It’s a proverbial English saying with no clear origin. Matthew Henry helped popularize it by using it several times in his widely-read book of explanatory comments about the Bible. The saying was probably inspired by Bible verses, possibly Matthew 13:13 (“Therefore I speak to them in parables: because they seeing see not…”) or Jeremiah 5:21 (“Hear now this, O foolish people, and without understanding; which have eyes, and see not…”).
How far are people willing to go in order to retain their illusions? Surprisingly far! Take a look at this TED video “The Dangers of ‘willful blindness'”, which I dedicate to those who are willingly blind, including those who truly believe I am going to back down from calling out their lies and deceptions while sons of perdition try to drag others down in their destruction: