The argument I've liked I saw years ago. Basically the vikings were the last people to experience true freedom before civilization covered the world. Imagine being on a boat with your buddies, sails at your back, wind in your hair, the stars above you, pissing in the ocean not knowing where you'll end up tomorrow. Maybe you'll raid a village and be set for life, get a few beautiful young wives, etc out of it. Or maybe you'll die, or maybe you'll be still sailing, who knows. But there was no one in the world to dictate what you could and couldn't do.