A 16 year old loses a fight to a 12 year old.
Goes away and comes back with a knife and stabs another (much smaller) 12 year old that the fight was originally with.
Just like the Thai that lost a fight to an Iranian in a night club, then came back with his gun and shot him dead said, he lost the fight publicly so had to come back with a weapon to win.
So many Thais simply cannot accept losing, especially to someone smaller, younger or foreign. Even if it ends up costing them their life, they either cannot compute that with their raging shattered ego, or knowingly rather risk dying a physical death than a social one.
A wounded Thai is a very dangerous animal.