It's not the rich getting richer, it's monopolists getting richer at the expense of non monopolists. When the strongest monopoly of all, money, ceases to be a monopoly through negative interest rates or inflation then the monopolists simply flee into the next best thing. There isn't just a debt cycle, there is also a land bubble cycle because land is the second most powerful monopoly.

Monopolists not only includes the rich but also average home owners whose land is appreciating absurdly quickly. The problem isn't with negative interest rates or inflation because those merely break the monopoly power of money.