Power is enacted through multifarious means, with wealth being one of them. Wealth isn't a requisite for power. Generally in the US, positions of power are held by men, because of (or in spite of) an interconnected system of laws, norms, and a history of (generally) men telling people what to do. And those gender-based ideas enacted in laws and norms and our culture have percolated through our society to affect everyone in ways we often can't detect.

The point is that yes, for these reasons and many others, we should "believe women when they report harassment in the workplace."