Why are people so arrogant when they are ignorant of the matter?

It appears like everyday I go on YouTube or some blog online that talks about something pertaining to race. This include things like crime in my city. I am an African American male from the ghettos of Detroit city so I am very aware that crime is high in the city. These crime are a product of narcotic sales and lack of Jobs. I myself am from a family of people who sold drugs for a living but never did it myself. Upon entering foster care at the age of 8 I was able to be place with foster parents in the Suburbs making over $200,000 a year collective so I have seen all kinds of lifestyles. I understand after moving back to the city that a lot of people did not experience things that I had a chance to so they never think aside the box. A powerful quote I always say is "If a person ate ramen noodles are their life they're not going to wake up one day a want a steak". I personally parade myself around alway wanting more in life like knowledge and experience. Every time I look up something pertaining to black people and crime I always see a barrage of negative racist comment. Some of these comments are from complete idiots but many are from educated individuals who seem to truly believe the racist comments they utter. It's actually not shocking since living in the suburbs around a lot of Caucasian people I have seen a mixture of racism and friendship. These kinds of things are important to me because it has allowed me to see that no matter how much I try to some I will always be a ignorant "N*gger" who is just lazy living of welfare checks. Why is this? Why are some people so arrogant as to think they know what it is like someplace they have never been?