The Joy of Programming

the pleasure of crafting something that is useful
"Crafting" through the centuries

creativity - in itself

the urge to create - from scratch
this mitigates against sharing and re-use

software as a "plastic" tool
(more than) chimps and other animals

The psychological urge
from early tool making by prehistoric ancestors
Prehistoric man made tools - it made his life easier and made him the pre-eminent "creature"
Tool making was individual - originally everyone did it
Tool making happened for millions of years - it became ingrained into the "genes" of the psyche
(but if so, why doesn't everyone do this ??)
Prehistoric man has always "created" too - in artistic and other manners

The "creative" urge manifests itself in myriad ways in modern man -not just "art" per se
Ditto for tool making
Much of science can be viewed as "tool making and creativity"
As can Engineering

So, for a subset of humanity, these 2 urges combine in terms of software development

Make the distinction about those in the ICT industries that have these 2 urges (tools and creativity) combined and present - versus those just working in the industry - managing, selling, etc.
Thus, for those who are "toolmakers" - which is many programmers (or even those who did program but no longer and just occasionally dabble), the "buzz" is the creation - from scratch, actually making the toll and seeing it used (even if only by themselves alone).
(Re)Using someone else's tool does not give this innate joy
Hence the persistent lack of re-use of/in software
Hence the constant change/movement - even progress - in software
Hence the difficulty in getting programmers to change their ways