I grew up in a wealthy white neighborhood in the 1990s. My neighbor was a Caltech/Stanford grad that needed help building some RF measurement equipment, which I did as a summer job during high school. That evolved into a job programming a driver for spectrum analyzers, which evolved into a job developing software for embedded systems. By the time I graduated college, I had a guaranteed engineering job and a bunch of connections in the field.
There were no black people in my neighborhood. I don’t recall any in my elementary school classes. Thanks to housing segregation—the legacy of redlining—they were elsewhere, in neighborhoods where there were few if any people with Caltech and Stanford degrees. You don’t think that makes a difference?