I don't think it's just hard work. It's about whether your parents - and you - know what to prioritise. It changes a bit generation to generation, but obviously some subjects are more academic and enable more opportunities, while others do not and aren't as 'academic'. If you are bright, do not have any conditions which hugely affect your ability to do most schoolwork (easily learn to read etc) and your parents know to prioritise/encourage focus in certain areas - or you happen to stand out in these areas naturally - then it's easier to succeed.
There are plenty of people who work crazily hard for very minimal wages, but were not encouraged or able to prioritise 'academic' subjects so will never get into Medicine, Politics, Engineering etc. whether in work or at University. It doesn't mean those people who do get in 'work harder', some of the hardest workers I've known are those who are working at the best they can achieve against huge odds. There's often some luck around supportive adults in some people's lives as well, whether these be parents, teachers or another adult/older sibling who takes interest. The child's peers can also make some difference.
Equally, those who have gone through severe trauma, been exposed to substances in utero, have SEN that makes daily life or school work harder, have parents who neglect in some way, live through war or similar, live in chaotic homes, struggle to build attachments, have to move families often, experience real hunger due to poverty, have MH issues and so on, often struggle. There are always exceptions, but those issues definitely feed into the overall outcome of the adult that the child becomes.
Also, I find it a bit depressing that he's in a Political party that has so many negative views around immigration and poverty, and that he himself 'heralds Thatcher as an inspiration'. To me, that doesn't say confidence and success. It shows a lack of understanding of why people need support, why they're living in poverty and a denial around the fact that not everyone can 'work their way up'.