[tpeo]

What I meant is that "economic" phenomena encompass a much wider range of phenomena you might be thinking of. It's the opposite of being restrictive: any problem at all where have something like an agent which has to choose something over something else might be considered an "economic" problem, at least from an economist's perspective. If anything like a ranking of choices can be defined as well as a set of possible choices, that's something an economist can work with.

About the Roman bit, the real issue would be how much of any direct monetary gain from conquest ended up in the hands of the Roman state rather than in the hands of private citizens.