Obviously, the idea of unhappiness is pretty broad, like from "my 401k is doing badly" to "I am unlikely to survive the day", but I suspect that it's true that if a certain threshold of the population answers yes to this question, that you can expect that a pretty large percentage of the respondents are probably in a pretty bad place, and if you have nothing left to lose, finding some way to soothe the pain of the end is at least understandable even if it's what nobody would prefer.
I am nothing even approaching a serious student of these issues, but I do fear that the lack of opportunities for Americans today to find a path to fulfillment with dignity means that many of us will wind up in situations where we are basically riding out the days until our death, and even though so many of the people consigned to this fate are not what we would consider ideal, I think we should judge ourselves as a society by how we address their issues.
Anyhow, Turchin himself comments on this matter in https://www.theatlantic.com/ideas/archive/2023/06/us-societa... , it's an interesting read.