This is the essence of the Agricultural Revolution: the ability to keep more people alive under worse conditions.
There is some truth here, but happiness is one of the key motivators behind evolution. People tend to do what makes them happy, so it is better for a species’ survival that the things that make us happy are also good for our survival. If humans were by and large happy with the hunter-gatherer lifestyle, why change? The decision to change has to come before natural selection.
