An accurate history?
None embodied this more than the Border Reivers who were a wild bunch living along the borders of Scotland. Quickly the Borderers found that raising crops only to have them burned when warring factions came through was a waste of time. Raiding livestock however proved to be profitable, as did their riding ability as skilled horsemen and guerrilla tactics.
During war in this area allegiance to any one side could mean death whenever a new ruler rose to power so the Borderers remained loyal only to their kin and clan. To make matters worse the rulers who employed them to maintain law and as the first line of defense would often deal with them harshly in other times when their lawlessness got out of hand.
All this encouragement of predatory behavior gave rise to a way of life based around their own strength, cunning, and gain at another’s expense. Combined with their defiance to authority you have the beginnings of what would later become Ulster-Scots in Ireland and the Scots-Irish in America.