As a black alum from MIT and feel I can speak to this anecdotally. Here are some distinction to keep in mind.
1) From the moment I stepped onto MIT's campus I was actively recruited by Silicon Valley companies. My freshman year was tough getting much attention, but recruiters would talk to me and generally gave off the vibe that I was wanted. Contrast this with going to a HBCU where these companies are not present on campus, or if they do show up its only for a day or two for a career fair. You wouldn't feel as welcome coming there.
2) I had black friends who were upperclassman who had "made it" in SV. They could offer advice and guidance. When I moved out to SV I also had them as part of social circle so I had social ties outside of work. Coming from a HBCU its likely you do not know anyone who works at these companies. You also do not know anyone who lives in the area to socialize this. If you do not relate to the people from work then you have trouble making friends.
1) From the moment I stepped onto MIT's campus I was actively recruited by Silicon Valley companies. My freshman year was tough getting much attention, but recruiters would talk to me and generally gave off the vibe that I was wanted. Contrast this with going to a HBCU where these companies are not present on campus, or if they do show up its only for a day or two for a career fair. You wouldn't feel as welcome coming there.
2) I had black friends who were upperclassman who had "made it" in SV. They could offer advice and guidance. When I moved out to SV I also had them as part of social circle so I had social ties outside of work. Coming from a HBCU its likely you do not know anyone who works at these companies. You also do not know anyone who lives in the area to socialize this. If you do not relate to the people from work then you have trouble making friends.