At the end of the day, it's about family.
Not entirely right, it is all about principle aka IDEA that you accepted to define yourself and you still live with it today.
Kamo (or manga author) decide to give founder GOAL to be a 'good son'. He holds principle of making his poor mother to live a good life.
Moment he see his mother get harassed by his whole COLONY, it is attacking his principle and honestly, if he is drawn as a bastard, he can choose to still be a jerk, continue the scam, keep raking the money to put his mother in a gold cage, redefining his principle and himself entirely, as how it is with many politicians today.
And this is exactly why MLM is bad, it can shape you out to be a heartless jerk, or someone who worships money and will not hesitate about the means or consequences.