Some of the posters here must live in another country if they have never seen violence in Thailand.
I have seen some horrific violence in person, some provoked, some unprovoked:
Student getting stabbed inside and outside Panthip Plaza. Blood everywhere.
Yaba'd up fruit seller on Soi 22 randomly stabbing passers-by until collared by Police. He had a go at the Police as well btw.
Bus driver assaulting taxi driver on Soi 22 with an iron bar after he got stuck trying to turn the corner and the cabbie wouldn't/couldn't move.
Korean tourists being laid to waste by bouncers outside Shark Bar in Soi Cowboy.
American expat having his neck broken on Soi Cowboy after a Thai kicked him in the head.
Fortunately never have been a victim of it myself.
Also had two friends murdered by their Thai spouses in my time here.
As to foreigners, I've drunk with murderers (later caught and convicted), Scotland Yard's Most Wanted, top football hooligans (Chelsea Headhunters), UVF paramilitaries, etc.