You should read the happiness report. It is not based on quite as flimsy foundation as you may think. They examine a lot of metrics.

We Scandinavians are not sparklingly personalities. So it is very unlikely that we too these lists because we are such positive optimists. Quite the contrary, we can be quite negative. I remember an American living in Finland remarking on how refreshing it was that being negative was totally fine in Finland.

If it was only about what people project, then the US should have beat everyone. There is a lot of pressure in the US to smile be upbeat, positive and believe anything is possible.

Not very Scandinavian. We are known for The law of Jante. Not what you would expect from societies projecting happiness and optimism.