I find it interesting that so many posters are saying private school. Maybe they're Tori bots or accountants pf struggling private schools 😆or perhaps it's the good old British class system. Private, or better still, public schools and then Oxbridge. However, those who inhabit this particular middle class sphere and end up not delivering on these snobbish familial and microcosmic expectations remain full of bitterness and self hate even if they are what most would consider successful. Offspring of successful middle class parents don't always follow their parents' trajectory at all, they can lack motivation and feel misunderstood with all the parental pushing.
The most successful children around us are actually from aspirational migrant families. At our local grammars it's 90%+ children with one or 2 parents born outside of the UK.
The seriously rich are often transnational global citizens taking on the top roles in the top firms. They don't go on about being successful though as to them it's just being, so a way of life.
It's also not really about hard work as such. It's about values and investing in the right activities. There are plenty of career opportunities in the job market. Those with confidence, interest, motivation, education and a open minded outlook will go and cease them.
In the UK it's a lack of general aspiration that keeps hold people back. Society here is still classist and there is a huge lack of equality and equity, this is only getting worse now.