The same question in 1800's china - why didn't they stop it?
Well, many people knew what was happening and some people tried, but the regime was too indebted, too bloated, too wrapped-up in palace intrigue and power-games in the capital, worried only about maintaining their own power. The elites felt it was a problem of peasants and lower-classes so far from them that it didn't matter. Eventually, China got their butts kicked militarily by foreign powers, civil wars broke out domestically, and eventually the emperor was powerless to control anything.
I hope we don't follow the same path.
China was a weakling then and they actually put up a fight but lost. They had the will but not the means.
We are supposedly the number 1 power so the comparison doesn’t jive.
We have have all sorts of means at our disposal to stop it... but lack the will.
So the two cases are opposites.
China had the will to stop but not the means. We have the means but not the will.