There’s a flaw here. A lot of people who believe they are “deep thinkers” and engage in this type of conversation are liberals.......and they’re miserable people.
It is not possible to be happy or cheerful when discussing the TRUE state of the world.
The study notes people who talk of deeper topics more often are happier. I suspect that happier people speak of deeper topics - that ‘deep talk’ results from happiness, not drives it. People who are financially stressed, depressed etc. are likely to just ‘get by’ in conversation. When their lives improve, then they have ‘time’ emotionally for reflection etc.