Declining life expectancy suggests a general increase in scarcity. If the processes around you are trying to make things more scarce for you rather than less, then you’re in something more like a conflict relation than a trade relation to them, and delayed gratification is much less feasible in wartime or other emergencies where you’re likely to die if you don’t get something done NOW.
What are the competing explanations for high time preference?
A better way to phrase my confusion: How do we know the current time preference is higher than what we would see in a society that was genuinely at peace?
The competing explanations I was thinking of were along the lines of “we instinctively prefer having stuff now to having stuff later”