How did European powers benefit from reselling goods to their empires at a markup?

so we all know european empires didnt really benefit from resources as much as reselling refined goods back to the colonies but how does that benefit a country exactly

they already have all the resources a country to offer so how does taking those resources and making it something useful and reselling benefit the colonial country

money isnt physically beneficial its something you exchange goods with so how does using ur factories to physically make useful things to foreign people help the country? idk if this makes sense