Despite the fact that most European nations colonized most of the world and extracted tribute for several years, what is the reason they are now struggling with their economy?

Its not like this is the first time europe has experienced economic struggles

These things are cyclical and there are a plethora of reasons and potential reasons that we definitely cant fully cover here in reddit comments

Lots of things like covid, the ukraine war, an aging population, brexit, natural disasters, corruption, shady financial practices, and ripple effects from other foreign markets like in asia and america all contribute as well as many many more factors