I think the hatred for JO comes from them both having a similar start to life - both sets of parents were very comfortably off. But he went and did the catering college/duck all money route, whereas she did the 'get a job off my Dad's back' route. And then he did fall on his feet with his now wife's job and connections to be able to get the first solo gig - but she sees the advantages he had, not the fact that he still started as pretty much potwash and it developed from there on the basis of him being good at it. If she hadn't packed in her original extremely well paid job (as though she didn't have parents or the money to afford a childminder), she'd have been perfectly happy where she was and would never have bothered a baked bean in public.
I'm not a JO fan, I don't attribute any value to kitchen implements or bottles of olive oil with his name stamped on them, any more than I valued a sugared almond pink pudding basin with Nigella on the box. But it does boil down to he chose a career path, did the tit times, did the college, caught a few breaks and all the way through, he has always enjoyed cooking and food. And most importantly for the fame and fortune side, he is good in front of a camera, as he has the ability (which he had right from the beginning) to make it appear that he is speaking directly to the person watching, not that he is doing a performance in front of people and it's all so artificial and weird and where do I look or speak.
She didn't chose this career path. She fell into it from a position of not wanting to do it and then saw the money. She doesn't even like food, never mind cooking. She doesn't have the training (available at an Adult Education Centre near you), the experience of cleaning down at 3am, having a chef tell you that your chiffonade is more like a bag of potato peelings and to do it again properly, of explaining very carefully what the chemical processes are that make it essential to cook onions slowly and gently before adding garlic. He's had people saying his ideas are tit - to his face, too. Hating a job, being tit at it and yet wanting the advantages it can bring is why she detests people who love their job, are good at it and benefit from the advantages of being good at it.
She wouldn't have lasted ten minutes at my secondary school. She wouldn't have lasted five in any kitchen I've ever worked in. Because they can't be doing with whining, wailing and 'I'm TOO GOOD for this'; if your boss tells you you're cleaning out the skanky back of the fridge and you need to stay until it's sparkling clean, you do it if you want to keep you genuinely crappy paid job. Thinking you're too good for anything is the guaranteed way to always be unhappy.