The comparison made me like “skillshitting” as an answer for the OP.
Then how about “biggish dickish”? My final offer.
I think it depends on whether you believe the speaker is being completely honest. If they are expressing a genuine preference for ready meals, then it’s not exactly sour grapes - it might be insular thinking, or it might be a genuine and completely earnest preference for ready-prepared foods.
If they are simply asserting that to avoid admitting that they failed to (or think they would fail to) attain the skill of home cooking, then it is sour grapes. It doesn’t matter if the grapes are attainable or not - only that the fox said they were sour after giving up trying.
There is, of course, always the very real possibility that there is no specific word or phrase in the English language for this phenomenon. Not that it’s not worth trying to find one, but this concept might just need to be described in its own sentence rather than forcing another existing term to cover it.
Many here are suggesting that the person knows it takes skill but is envious or is being a dick.
But I don’t think so. I think in most cases the person is completely ignorant of the skill involved and assumes it must be trivial.
Witness how rare it is for people to be dismissive of a skill that they themselves have studied for a while.
Yep this. Just like all those “What fallacy is…” threads (although I think I once started one of those).
As a slight detour, if not hi-jack, there’s ‘strategic incompetence’ - back when I worked as an electronics repair tech, I very specifically did NOT learn how to bugger cable-TV boxes for free movies, so that my friends would stop asking.
Not a phrase, but in the Engineering / IT world, this Dilbert cartoon is famous for illustrating this 
https://dilbert.com/strip/1994-10-17
“Whatever I don’t understand must be simple.” – Dilbert’s Pointy Haired Boss
And there’s a third possibility, which is what some of us are trying, apparently not always successfully, to describe in this thread: again, that the speaker is sure (usually inaccurately) that the skill is very easy to acquire, is sure (very often also inaccurately) that they could accomplish it with no problem, but does not think that it’s worth doing. They have come to this conclusion without ever trying to learn the skill; it’s not a matter of having tried and failed.
This is true. There are a number of concepts that English has no word for; and some of them seem difficult to explain clearly in English. (I suspect the same general phenomenon is true of other languages, though the concepts/missing words vary between languages.)
“I started by reasoning that anything I don’t understand is easy to do.”
Yes, that’s pretty much it, exactly. – well, maybe not exactly: people will often apply this principle to disrespected work, but not to work that’s highly respected and well paid.
That does border on the Dunning-Kruger effect - especially if it’s a case of “I’m sure it must be easier than everybody says”
I’m starting to lean this way myself (and BTW, many thanks to everyone for having a go). If this is the case and a new word is needed
- I think this is the leader in the clubhouse.
j
He has a wife, you know.
I think this is correct, since if there were, we would have found it by now.
This often shows up in academia, toward administrative skills. Professors (and, I presume, other professionals with advanced degrees) often assume that the skillset held by the people “beneath” them on the org chart have trivial skills and are fungible. They would never stoop to doing such tasks, as they, like those who perform the tasks, are beneath them.
Then the opposite shows up, with similar effects: some professionals condescendingly praise those skills as arcane and mystical, as if they couldn’t possibly learn how to unclog the copy machine or brew the coffee. or submit the check requisition form. This praise conveniently excuses them from ever stooping to perform such tasks.
“Pull a Sheldon Cooper?"
It happens the other way, too, though. I have family who basically have nothing but scorn for a man who can’t work with his hands, and it wouldn’t matter if he was a doctor rocket scientist: if you let someone else change your oil, they will be contemptuous.
This seems to capture it pretty well! Doesn’t necessarily capture the motivation but there could be several different reasons for skillshitting that people have fleshed out nicely in this thread.
I like both floccinaucinihilipilification and skillshitting.
To me it’s different to sour grapes - that implies the person wants the skill they’re claiming is worthless. But I have met people who are like the OP’s example, just not into cooking - or eating, beyond the basic needs - so disparage it as a skill. And I know tons of nerds who genuinely think that sports skills are worthless, but it’s genuinely not because they wish they were good at sports.
FWIW, floccinaucinihilipilification was a word that came up a few times on the British quiz show Countdown when I was a kid, so it’s a fairly well-known word among a certain demographic here. The resident lexicographer, Susi Dent (who is still in that job), pronounced the first cc with an x/ks sound, and the next c as a voiceless s. The “nau” part was like the word “gnaw,” but shorter, not like the word “now.” The rest would be phonetically read out however your accent usually pronounces those phonemes.
I think Sheldon’s brand of dismissiveness is what TV Tropes calls Hard on Soft Science.
Isn’t it just ordinary narrow-mindedness? “I don’t care about something, therefore it’s stupid.”
When I see something like “Flocci…” I say “flok - chee - …”