Question

The greatest enemy of knowledge is not ignorance it's the illusion of knowledge

Answer 1

This line was said by Hawking.
He means that someone who does not know something is better than the person who thinks he knows it, regardless of what either actually knows.

An ignorant person can be given education. He can be taught. Hell, we were all ignorant as one year old babies, but we’ve been educated, so now we’re a bit wiser.

An arrogant person is much harder to deal with. He cannot be educated. He refuses to be given knowledge, he refuses to question his beliefs because he thinks that he is right all the time.

You see the second type of person a lot on Quora. He asks for answers that confirm his beliefs. He refuses to see the other side of the story.

Hawking is saying that open mindedness fosters the intake of knowledge.