It seems like Maslow's Hierarchy of Needs and basic economic calculus isn't included in your conception of how holidays came to be.
Frankly, neither of us can honestly assert why the holidays came to be what they are with anything remotely resembling full confidence, however, some narrative explanations of how the holidays came to be are very logical and others are not at all logical. I am prone to go with the logical narrative that accounts for things like sustenance, survival, and praxeological considerations.
First, the astrological markers are established, i.e. solstices and equinoxes. Eventually those become associated with growing and harvesting seasons. The anchoring of growing and harvesting cues to equinoxes and solstices was a way for people to improve their yields/harvests.
Eventually, the knowledge of why the holidays became largely, if not entirely, lost and the holidays themselves remained. The association with fertility remained for example, the Easter/Esther/Ishtar celebration which is tied to the Vernal equinox. Then people unskilled in the application of the Golden Rule started engaging in post hoc ergo propter hoc logical fallacies and chose to associate their greater harvests not with intelligent planning but rather with divine intervention. That leads to all sorts of weird, nonsensical rituals and insane justifications for them that often become ossified into tradition.
I mean...just look at how far baptism has come. The distortions are literally ridiculous. Over a billion people practice baptism today and think they're doing something but the truth is that what they're doing is a hollow shell of the original ritual. Holidays are the same.