2. China has a surplus of people that causes various issues. Losing some doesn’t hurt and actually helps there rule. 3. It is a perfect cover to eliminate political enemies. 4. It strains all economies but they will figure it affects more primitive ones less than the more the highly developed like the USA. 5. If it kills off the older generation it speeds up the political shift to the left and socialism. The older generation are more conservative and that makes them a target. 6. If it destabilizes the US enough it could force their nemesis Trump out of office. With the Dems in control the Chicoms can revert to their most favored status.
As you can see this is a Win-Win for the Chicoms all around.