There are plenty of awful regimes around the world, but China is unique in how powerful and dangerous it is.

In particular, if China were to invade Taiwan, which it has a stated intention of doing, then the TSMC chip fabs—the only place on Earth capable of mass-producing modern electronic circuits—will almost certainly be destroyed in the fighting, and that will cause a global economic depression that'll make 2008 look like a minor inconvenience. That's a huge global threat.