Cut throat competition at UC Berkeley

I keep hearing about the cut throat competition at UC Berkeley. How does this manifest itself? Do your classmates refuse to help you or share notes if, say, you missed a class as you were sick…
Please give some specifics to explain cut throat competitive behavior?
I go to a very collegiate HS, where we help each other out all the time, can’t imagine not continuing to do that in college.

Probably should re-post under University of California-Berkeley