When people think about China they tent to assume that China is somewhat similar to a western country going thru the afterwards of some sort of overheated boom. Say the US from 2002 to 2007 and the big recession of 2008-2010.
But China is not mature and developed like the west.
Sure the east coast has nice modern cities which look like the cities of any Western country. But large parts of the country are still poor, rural and remote. When construction goes on here, a modern road is built where there was nothing before cutting the transport time between two cities from 5-10 hours to 1 hour. Houses are built for people to work in the city doing high-productive factory jobs where they before were doing small-time farming in the country side.
This is a massive lift in real economic activity which can finance a lot of debt.
Completely incomparable to the expansion of credit to low-income families to finance housing that gave the boom in the US and other western countries from 2002 to 2007.
Secondly there is a now huge upper middle class who are travelling the world, sending their kids to Australia or US for study and still buying Apple products. They are not going away. And ultimately they will change China into something more driven-by-internal-demand, civic, modern ... even democratic.