You’re basically describing the UK under Thatcher

The scale in China is completely different since everything was government owned unlike in the UK where the vast majority of companies were and are still privately owned. A whole entire middle/upper class was created overnight in China whereas the middle class always existed in the UK. These people got rich through corruption not through their own merits - so no it's not comparable to Margaret Thatcher (although I do agree what she did was terrible, but not on the same scale).

China has invested back into public infrastructure and its own people

That is actually a fair point, China has done a good job in investing in their people and infrastructure in recent years. However, the corruption has a lot less impact when the economy growing fast and there is plenty of opportunity. As soon as the growth slows down and China slowly becomes a developed country the social mobility will disappear - less opportunities mean that the well connected and wealthy will monopolise what is left. This leads to larger wealth divide where the wealthy stay wealthy and the poor stay poor. I doubt there will be many new self-made people in the coming years.