If you know someone and you screw them over, just for a few more dollars, its 100% personal. Every person I've met that says its not personal, is just trying to cover up for their lack of morals.
Perfect example is from that BET show 'Rules to this Shit'. When that dude was the beard was talking about how Puff was his friend, but one day tried to have him sign a contract that would of gave Puff everything & him nothing. Good thing he could read and didnt sign it but Puff just shrugged it off and said "Its nothing personal, its just business". Dude still hung with Puff after that, which shows 2 things, 1.) Puff is a snake & 2.) homie is a sucker.