The discussion here is about happiness. Discord among the population does not bring about happiness. According to the chart posted, Finland is the happiest country on earth. It is also one of the least diverse along with the other countries in the top 10.
It could be because they aren’t fighting about every issue because they at least have a common goal and agree on fundamental issues. Having small disagreements and discussions about rather insignificant issues is to be expected and even encouraged, but Democrats and Republicans in this country are not even close to being on the same page. One is patriotic the other is not, one supports Christianity the other doesn’t, one supports unfettered immigration the other doesn’t, only one supports abortion, one believes the government should be relied on more heavily the other doesn’t, one believes taxing heavily those that make more money is the way to help those that don’t/won’t work, one believes the government should provide healthcare for “free” while the other believes the private sector is the answer, etc, etc, etc. Countries like Finland don’t have these issues. They agree on the major issues and discuss the details. If you want to call that group think, then so be it.