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.