The elites of the West deprecated nationalism, claiming it was archaic.
They replaced it with a globalism that turned nations into an empty containers bounded by 'enlightened' bureaucratic laws and rules.
By doing that, they removed a stable form of tribal decision making from our social stack.
Tribal decision making is an essential element of social decision making, it provides social cohesion, coherent group decision making, and internetwork trust.
Without nationalism, countries became easy to corrupt (the amount of social and economic corruption we've experienced is staggering)
Additionally, in the vacuum left by the fall of nationalism, a chaotic networked tribalism arose around every identity -- from race to ethnicity to religion to sexual preference.
Now, as social order falls apart, we find that without nationalism, nobody is willing to risk their lives in the defense of hollow bureaucracy.