I went to a state school, and my entire professional career is due to the friends I made there. College was a very rough time for me, and I wasn't getting many interviews with my resume (really poor GPA, no internships, no extracurriculars, etc). A friend hooked me up with a job at a startup and landing interviews since has been no problem.
This isn't a glamorous story where my network made me a millionaire, but my life would be much worse having not made those friends back then.
Internships definitely help (GAFAM uses them like extended interviews for full time offers). I also think it helps that my gpa was ok (3.05) and the school i went to (purdue) was highly ranked enough and big enough that we had entire recruiting teams come out to our career fairs which is where I got my first internship. Some companies even sent out employees for an entire week to our campus to do interviews for internship and new grad hiring.
This isn't a glamorous story where my network made me a millionaire, but my life would be much worse having not made those friends back then.