Well if all IAP buyers would collectively decide to buy comic books instead, and all IAP programmers would decide to switch careers to comic book illustrators, the output of comic books would be comically high. So I'd say it's a shift in spending, mostly.
"But!" you may say, empathically, "these programmers lack not just self-respect and purpose in life, but artistic skills as well". I'd say it doesn't much matter – they'd probably find some other work, and the money would find some other purpose and the net difference would be "how much more efficient were they at producing IAP content vs. their second best job option" and "how much worse is whatever consumers buy instead of IAP content".
"But!" you may say, empathically, "these programmers lack not just self-respect and purpose in life, but artistic skills as well". I'd say it doesn't much matter – they'd probably find some other work, and the money would find some other purpose and the net difference would be "how much more efficient were they at producing IAP content vs. their second best job option" and "how much worse is whatever consumers buy instead of IAP content".