I can't, because the overlap with politics certainly happens in a number of contexts. One question we economists do not routinely address is "where do the preferences we study come from?" Often times preferences are politically motivated.
I think what you're missing is that money is one type of power, and that basically the study of economics, politics and culture are all just different ways of studying human relationships, of which inequalities of power are a crucial part. There are two broad types of relationships: relationships of rough equality and relationships of gross inequality of power. The latter are almost always abusive, because if you are in a position of much greater power than someone else, it's just too tempting and easy to take advantage of them. Preferences have little to do with it.
Preferences are the starting point of economic analyses, under the assumption that people pick what they want after who-knows-what a priori decision process.
Money (or, more commonly, assets) is sometimes included in models, but is not a starting point. If you're looking for models where solely wealth=power as an entry point into the field, I suggest political science (mentioned above) or finance. Overlap with economics in toolkit and occasionally questions, yes, but not composing the entirety of economics.
Consider the question the Obama administration faced in 2009 (and the EU then and later): "Should we inject a large fiscal stimulus, or revert to austerity?"
Very obviously, economic and political issues are inextricably intertwined there.
Your notion that economics is a pure, purely descriptive (and somewhat predictive) "tool", while politics concerns itself with values, is not sustainable.
