They didn't capitulate to western powers, and are in fact still at war with them. Plus it lets them demonize China by proxy, which is always something western powers are looking to do.

Also all that is exacerbated by the fact that they are fairly isolated and not many people go there. People propagandaize about China all the time, but that is always in conflict with the fact that many people can and do go visit and see the reality for themselves. Not nearly as many people visit the DPRK, though if they do they will also find out it isn't remotely like what they have had.