There was an interesting theory in a paper: during happiness research they interview people and ask them to imagine what the best life would look like and then estimate where they are compared to it in a scale of 0 to 10.

Well, in Finnish comprehensive schools we use grading 4-10 where 4 is "failed", so everything under 7 is bad and 8 is merely "ok". And as we learn this odd scale quite early it's stuck in our heads. So yeah.

I don't know any Finnish person that would describe their life as happy. Perhaps we mean to grade our life as merely tolerable when asked and the scale doesn't take into account this weird system that we use!