The basic fundamental is that people are more likely to here your voice if you are more wealthy because your money allows you more access to better tools. For example a wealthy man is able to afford better lawyers than a poorer man and even though both sides will be heard a decision will made based on how well the defence or prosecution is able to deliver your case. Is it not true that a better lawyer is able to do this more effectively? Good lawyers cost a good amount of money. Thus can you not say that justice depends on how much money you have?
Wealth is power. Power to persuade governments on what policies to pursue and in so doing marginalise democratic ideals. Inequality breeds contempt. Contempt of the poor by the rich, contempt of the rich by the poor. Laws initiated to lift the burden of poverty are trampled by the interests of corporations acting in the interests of investors. Your vote can be bought, not with cash filled envelopes but by misinformation and publicity campaigns. Indirectly or directly democracy suffers from wealth inequality.
I don't have an issue with people working hard and building their buisnesses, that's capitalism, it doesn't hurt democratic ideals either. But if corporations are killing people because they are not functioning safely, and destroying people health because they';re too cheap bto not destroy the environment, we have an issue, because last I checked all men were created equal, and they wre endowed by their creator with certain unalienable rights wich are being infringed.
Wealth equality, rather than inequality, is what harms democratic ideals. Equality is treating everyone the same, all across the board. This denies people the basic democratic ideal of economic freedom. It is because of this that wealth equality is a bad idea. Everyone is given the same freedom to earn more money, just not everyone takes that oppertunity.