His resolve, is blind, and one-sided, absolutely one-sided.
His goal, is pointless, only "beneficial" to him, but it will never satisfy him.
He'll get over the death of his clan, and when he realizes how terrible his actions were, he'll suffer from utter loneliness, and eventually commit suicide.
A boy who kills everything he's ever loved, in order to benefit himself, results in loneliness and pain.
Revenge can't cure pain, it simply stabilizes it,and converts it to loneliness, but time and embracing love can make the pain lesson, gradually.
For Instance, in 20-30 years, once he's slaughtered all the people who welcomed him with opened arms, he'll realize how pointless and stupid it was, and kill himself.