The psychological explanation is found in the age old fable of the fox and the grapes.
Because the fox couldn't reach the grapes, it dealt with the emotions of failure by declaring that the grapes were not actually worth having, and so not reaching them was actually a kind of success: dodging the disappointment of making even more effort to get to the grapes, only to discover they are inedible.
In the English speaking world, we have condensed that lesson down to just the two words: "sour grapes". When it's obvious someone is coping with cognitive dissonance in that way, we say, "oh, that's just sour grapes!".
Someone who has given up on themselves as a developer because of AI just declares code, and caring about code, to be "sour grapes", so that they have a rational explanation for their abandonment of code and coding that doesn't feel like a personal failure.
"sour grapes" is related to "burning bridges". When people are forced to adapt to something new, or even do so willingly, the weak-minded ones feel the need to disparage the alternate reality in which they continued with the previous situation or way, along with the people who still continue that way.
Some immigrants slag their country of origin. It helps them live in the new one. The government in the old country is corrupt. People are assholes. It's better here, now. Everyone is nice. I like my new life.
Or, have you ever seen this:
"I'm leaving the community of this programming language and won't be making much use of it any more, even though I was a core developer. Here are the 17 problems with it, which, believe me, is not easy to say ... "