For a medical study sure, for a subjective field where society and culture play a major role, even N=1e7 of individuals living in the same country wouldn't be enough to draw a conclusion on the entire human population.
>wouldn't be enough to draw a conclusion on the entire human population.
Which is why the study does not draw a conclusion on the viability of all religion, it merely says that it doesn't see much evidence that religiosity leads to life satisfaction. The author even notes "these results need to be evaluated within the context of the study." Hardly the wholesale dismissal of religion you claim it's making.
