I remember two breakdowns while going through Computer Science and Engineering at UTA ( far from a top-tier school, we liked to call it "UT Almost" ) in the late 90s
1. a student in physics broke down sobbing during the final, like uncontrolled wailing. The TA helped her get up and walk out
2. in the discreet structures course a student got up, walked to the front of the room in tears, tore up their final in front of the class and prof, and then walked out.
3. not sure if it counts but in that same physics class from #1 another student threw up all over themselves but sat there in it and finished the final. maybe just sick idk
a lot of students are hotshit in HS and then get to college and find out they're not as smart as they thought. heh i came from rural TX armed with Algebra II and didn't even own a computer. Fortunately for me, i somehow ended up with a handful of upper classmen friends who seemed to make it a mission that i get through it. I owe them so much.
EDIT: Professionally, i've been on plenty of conference calls where peers break down in tears. There's only so much pressure a person can bear before nerves just give way.