The answer to the OPs question about Scandinavian countries being happier really isn't rooted in their economic policies or their politics. The answer lies in the fact that for most of their history they have not been affected by multi-multiculturalism. The same is also true in Singapore and Japan as referenced in the OP's original post.
In Scandinavian culture people are expected to work hard and be good citizens, not wards of the state or welfare bums. The overriding culture is one where you take pride in self sufficiency, and lazy or entitled expectations are not only frowned on---they are scorned by the culture. The exact same way it works in Japan.
So no, this is NOT a race thing, or a political thing, it is a cultural thing. And despite people like Bernie Sanders' insistence that America could be like Scandinavia ignores the fact that Scandinavia doesn't have cities like Oakland, Baltimore, Compton, and Queens.
So who wouldn't be happy in Scandinavia---- or at least the traditional one as it has been?