Q: Why can't Western nations "mind their own business?" A: Because they have no business to mind.

Sensible and common-sensical people from places like the USA, UK and France will often wail: "But why can't we just mind our own business?" 

Meaning, why are we intervening/ interfering abroad; when so much needs to be done to sort-out our affairs "at home"?  

This, especially, when it comes to engaging in wars on behalf of nations with which we have no treaties; or intervening to replace the rulers and change the way of life of... anywhere we fancy, anywhere in the world... for as long or as short a period as is convenient to us. 

But the simple answer is that we cannot mind our own business because we have no business to mind. 

For instance; what, exactly, is the business of the UK? 

(I don't mean to ask what our business should be, but what our business actually and currently is?) 

To which we can only say - there isn't anything At All: No actual business... Not so far as the people who run the UK, and their obedient managerial-state minions are concerned.

At least, there is no positive business... 

The fact is that our rulers (e.g. in politics, finance, mega-corps, and the mass media) are already sorting our our affairs "at home" in just the way that they want it sorted. 

That is: they are replacing the native population with immigrants and encouraging hatred between them; they are destroying the economy and the environment; and have already captured and corrupted the military/ legal system/ policing/ education/ health services/ churches.

Their home "business" of civilizational and social destruction is going very well, therefore they are "minding their own business" - i.e. the business of destruction; so (from their perspective) they are free to engage in similarly-destructive foreign adventures to their hearts content!