If you only want to work, why live?

It's similar to how construction workers aren't contributing to the fields of architecture or structural engineering in any meaningful way (beyond causing actual buildings to actually exist, but only ones that other people had already determined were structurally sound and possible to build). And, of course, they're contributing to humanity, which needs these buildings, and they're making the study of architecture and structural engineering useful for a practical purpose.

Similarly, just being able to write software competently allows you to contribute to the world benefiting from the use of computers, but it's not really the purpose of a CS degree. About 25 years ago, my CS department started teaching a programming class for non-majors, because, these days, biologists are going to write programs to apply their knowledge of biology, and you'd like them to write those programs well, and the CS department figures out what "writing programs well" means.