How many people got their lives ruined because of a bad school violence case? Legit question. I'm not Korean so I'm not sure how things work over there but it seems strange to me that at age 30, companies and employers ask for your middle school resume. "Sorry we can't hire you because you've been naughty at 12". Sounds a bit outlandish to me.
I don't know about half-way high schools, half-way colleges and half-way good jobs but what's so wrong about that. It's the lot of many people and there's no shame to that. Not everyone can become a doctor or an astrophysicist anyway.
Lower tier school violence cases? Kinda depends.
Higher tier school violence cases, it can definitely nuke your chances of getting into a good school.