Who needs a PhD for a "junior python developer role". Is it really necessary. This "python developer" idea sounds like it only applies to a small slice of PhD programs, notably the ones focused solely on computers. For example, what percentage of PhDs in molecular biology choose to become "junior python developer". When someone who believes a computer performing pattern recognition equates to a child having feelings and sensations^1 can become a "senior software engineer" at Google,^2 why is a PhD needed.
People get PHD’s because they love the subject matter and can get loans etc. But they then have a PHD that might not actually be worth anything and still need to eat.
Assuming just because you have a PHD means you need to use it is a sunk cost fallacy. Starting over can be a completely rational choice.
Does sunk cost fallacy apply to an assumption that because one has an ability to program a computer one must use it, i.e., demand pay for time spent on programming, e.g., with the end goal of coercing people to surrender personal data and/or click on ads.
Perhaps the value of a PhD is not limited to its "market value". I hope that part of the intrinsic value of a degree is an ability to think critically, unlike the "senior software engineer" example I cited, for which the "market value" is probably quite high. Sometimes markets are not rational. Myself, I do not care what any job market suggests. To me, education has value, both for the individual and for society at large.
"Tech" companies are not well-known for fostering crtitical thinking ability. Most of the world is eating, and feeding families, without knowing how to program computers. It has been that way since the dawn of humankind.
The majority of programmers work outside of the personal data collection and or clicking on ads sides of things. Advertising supported businesses are a fairly trivial slice of the economy, as should be obvious because it’s ultimately dependent on advertising spend from other companies.
Assuming just because you have a PHD means you need to use it is a sunk cost fallacy. Starting over can be a completely rational choice.