This isn't really true in the sense you think it is because the corollary of the marginal cost of software being close to zero is that someone only needs to cod

This isn't really true in the sense you think it is because the corollary of the marginal cost of software being close to zero is that someone only needs to code a quality opensource competitor once to materially impair the value of some software. What is really driving how well programmers are getting paid is several companies (google, meta, microsoft, apple, et al) managed to get big enough (probably temporarily) to gain vastly outsized profits from the mechanism you outlined above and they all had a policy of drastically overpaying for talent in order to keep said talent from going to a startup that creates the next idea that destroys their outsized profit machine. This was supercharged by way too low interest rates driving private equity valuations on companies that have no hope of actually achieving profits commensurate with their valuations also desperately overpaying for talent in the hopes that they can create the next big thing fast enough to catch up to their valuations. They weren't that worried about their burn rates because the low interest rates made it easy to raise more at very favorable terms at a higher valuation so everyone was happy. The latter trend is coming to a hard stop right now with higher interest rates (likely higher and for longer than most people think) and the former is also starting to change, so expect broad material weakness in programming salaries going forward.