From that usage your claim makes much more sense.

Willpower in my usage is more general, when impulses are overridden or circumvented. In your example, it includes the conspicuous consumption of which you describe, but also more subtle costs like the cognitive computation of determining the "why" and forestalling the impulse to remove internal or external factors.

My main point is that willpower is a limited resource that ebbs and flows during cognitive computation, often due to changing costs. But it can be trained up, conserved, and refreshed effectively, if certain hazards can be avoided.