The pillaging was actually only a very small part. The vast majority of going Viking was pure trade or, when conquest was on the table, colonization. That's how you get the Rus Vikings. When a bunch of pagans see unguarded temples, though, all filled with gold, and their gods would be pleased by the offering of such things? Yeah, they're going to pillage. It was often far easier to just trade with the people already there, and so they did. The idea that they're all there to make blood-eagles and die in glorious battle is ridiculous. They had a complex civilisation that set up many of the mediaeval trade routes throughout Europe and into the middle east.