For a people who are very anti social they do like their social programs.

They don't really have a reputation for being lazy, but that can be because there are so few of them that they don't really have any kind of reputation.

There could also be other explanations. For one "viking" only means "pirate" and is not a people the way that mongols are. All peoples have some members who become criminals, but that is not a normal behaviour. These were just the criminals from several countries who just happen to all use boats to get around, meanwhile the majority of the people from that region were farmers or fishermen.

It could be that the viking reputation is amplified by the fact that they raided monestaries which made them an enemy of the church which had the most powerful microphone of the day. But they were actually a very small portion of the population.

Or it could be that the decendents of vikings are lazy but are also inteligent enough that they get away with it by becoming administrators.