That there are still significant audiences for those who promote obvious nonsense – from creationists like Ken Ham and Ray Comfort to anti-vaccination lunatics like Jenny McCarthy and Robert F. Kennedy Jr. or proponents of crazy political notions (take your pick) – is testament to the fact that the human brain is a product of evolution and that evolution does not necessarily produce optimal solutions. That, is the human brain has significant weaknesses.
Scientific methods of investigation have been specifically designed to compensate for the shortcomings of our brains but they are not able to compensate for the fact that some people choose to trust bullshit more than they trust science.
It comes down to values: reason or faith? Pick one.