The charting section of the report has a great set of data:

https://data.worldhappiness.report/chart

One thing I noticed, comparing the US to the top ranked (mostly Nordic) countries: There was no clear pattern in "positive emotions" scores. Indeed, the US might be above average. But the US was far above the Nordic countries in "negative emotion" scores. So perhaps it is more accurate to conclude the US is "more unhappy" vs. "less happy".

Also the variance in the US was much higher - so it's more a subset of the population dragging things down.

This is consistent with a story that the major factor in the rankings is that the support and security of Nordic states reduce downward variance in unhappiness (e.g. for the poor, & sick).

Of course there could be many other explanations too (e.g. the US having a competitive culture where people who don't succeed above average are less satisfied).

(Too bad no one will ever read this comment, due to HNs recency bias).