The Apostle Paul wrote of this:
Satan, who is the god of this world, has blinded the minds of those who don't believe. They are unable to see the glorious light of the Good News. They don't understand this message about the glory of Christ, who is the exact likeness of God. 2 Corinthians 4:4.
We think this has to do with the Gospel of Jesus. That is true in part. What is not true is that is the only blindness that is out there. There is progressive blindness. We start out in truth, but because of outside influence and pressures we end up receiving blinders. It is very hard to avoid.
Why does satan try so hard to blind the people of God ( his main target). He has already fully blinded unbelievers, he doesn't need to work on them any more. He can not blind us to truth, but if you read the scripture, we lack the ability to see the glorious light of the good news. There is plenty of bad news. Good news is what we don't see.
There is plenty of truth and good news, but like in the Matrix there is reluctance to emerge. In fact the Matrix has some good things to offer it's prisoners. In one scene from the Matrix Cypher is eating with Agent Smith and says, "I know this is not wine, and I know this is not steak, but it's wonderful". He was practicing intentional blindness. Comfort is more important than truth.
Most people are blinded because of convenience. Because they don't want the pain of facing the reality of what they are missing. This is what blindness does. Traps us. Captures us. It is satan's plan to keep us from truth that sets us free. He is the slave master of all who refuse to believe the truth.
It is hard.. but truth is out there.. if we only will receive and believe.