I wonder how much of this drop can be simply explained as having reached a certain industry maturity. I assume at some point most of the fundamentals are in place, so we need less people?
Programming isn't an industry, per se. It's a skill, like accounting, sales, communications or law. There are definitely many businesses for which it's a core strength, but any large company has some need for it.
Maturity is definitely an issue. If you listen to what the industry is selling these days it's pretty much just AI. Before that it was DeFi and VR. There hasn't been a new smartphone since.. the smartphone.
