So if we take for granted that humans really, actually do seem to like free stuff more than we “should”, then perhaps instead of reacting with “lol, humans irrational”, we should more thoughtfully consider why evolutionary pressures would sculpt a mind that seeks out a “free lunch” over a cheap lunch.

Or, to rephrase, if free-seeking is such a powerful effect, then evolution must’ve intended our brains to work this way. Thus suggesting that, while the effect creates individual decisions that are economically irrational, over the long term it must be a survival benefit.

There’s a lot of ways this could work (and I’m eager to hear HNers speculate) but one that springs to mind is thinking in terms of risk as cost.

Imagine you must choose getting great fruit by climbing a slightly unsafe tree, or eating mediocre fruit on the ground in front of you. Over the long term evolution should favor the creature that eats the no-risk ground fruit over even the very low risk climb. Taking ZERO unnecessary risk would be favored, because even the tiniest risks are survival filters over evolutionary time scales.