The economic incentive just attracts people and it was obviously working because the archaeologists during this time period in scandinavia are finding tons of stuff. Wealth is transferred from places that do a lot of writing and chronicling to some of the places that don't including non-Christian areas. By the eight forties a change is evident and the histories will talk about it certain elements that had been part of the standard operating procedure in Viking attacks turns into something else. The hit and run aspect of this sometimes turns into a hit and stay with sort of overnight winter camps meant to perhaps help these Vikings avoid a terrible rough you know worse than usual weather trip home.