Yes, China has a lot of people albeit this number has been overstated for years (see above). But they are strategically landlocked and hemmed in by the United States and its allies. China now has the largest navy in the world in terms of its sheer number of hulls, but they have very limited range. Any conflict that takes place within 1000 miles of China's shores would see some Chinese resistance, but beyond that? The Chinese simply don't stand a chance.
Putting It All Together
There's much more to discuss on the subject of China's coming collapse that I won't discuss here including the lack of value add in Chinese manufacturing, rising labor costs, etc.
But the big takeaway from this article is that China's growth is dependent on food and energy, which they already have to import to cover shortfalls. This makes them highly dependent on the safety of the seas, which the US has guaranteed for the last 75 years or so since the end of World War 2. There is evidence that the era of the US sacrificing itself for the good of global trade is coming to an end. In fact, it can be argued that China's rise has only been possible because of the US's protection of ocean transport.
The Persian Gulf is a long way away and there is no way the Chinese can guarantee safe passage of their own oil imports. This threatens the stability of their current political system as hungry and unemployed people tend to overthrow governments.