Does this help at all: DH's mum and dad: teacher (former headgirl), engineer and organist. Both thought schol was the be all and end all. Scoffed at trades, scoffed at commerce, scoffed at people who worked in offices as boring, anti materialism. Counted o'levels and bragged about thejr children's achievements. All 3 went to a Russell Group Uni. Both DD's have never done anything other than menial work, o e in shops one as a TA equivalent. In our 20s their mantra was "ugh what you do is boring, I couldn't work in an office". Neither had any direction or any will to work for money with a much cleverer than thou attitude. DH on the other hand was very close to the neighbours, who were childless and lived a better life and was influenced to make something of himself in the world of work.
(Although his sisters regard him as a capitalist bastard and his mother does a cat's bum mouth every time she comes "people like us don't live like this.") Drains the joy as do the sils (one more than the other)
My family on the other hand - farmers and racing. Not an academic qual between them until mother met father. Loved nice things, knew how to maximise income, see an opportunity, travelled, socialised and taught me how to handle the labourers and the local gentry. At 17 I could dress, make small talk, drive a car, ride a horse, shoot straight, type and boil an egg. MIL regards me as thick as mince.
I dropped out of uni but earnt 6 figures for 10 years from the mid 80s, retrained at 43 and at approaching 60 am on 6 figures again. I have learnt I am clever, not a genius but alright. Much of success is about relationship mgt and that is what I'm very very good at but it's what my family taught me almost like an apprentice.
The academics help but they don't teach work or life skills. And without the life skills, expectations, drive and confidence the academics aren't enough. DH was 27 when we met. I had to teach him to work a room, top up a glass, carve a joint, use his irons properly, and sort out his wardrobe. TBF he wasn't that bad but he wasn't polished and in his field he had to be. He has a brain the size of a planet but he needed that little push to do the social stuff - which he still hates but I have no doubt it tripled his earning power on the way up. Now he has a reputation it doesn't matter a jot.
Overall I think the academics are important and the life/social skills are important. But I think you can be more successful with the latter alone than with just the former. With both the world's your oyster.
Looking at our two DS is alpha, huge network of friends, took a first, has worked on a farm before uni and a year for a small business after. Doing a masters, working for same small business two days a week and has one small business with a few chums already and has just bought a domain for his second
DD every bit as clever, introverted, has ADD, struggles with social events and prone to anxiety/depression. At an equally good uni but I doubt she will fly at work. However she and we know that and already she is looking at careers that will suit her - academia, curating, possibly specialist teaching (she learnt BSL in her gap year).
So some of its nurture and some nature. I suspect one of the sils is similar to dd but because she was clever and her parents "quaint" it wasn't picked up and she was never encouraged to make the most of herself. At least dd knows to stand up straight and smile when confronted with a social group.