At the risk of being shot by, and with apologies to Carolyn, sure!
Let's take business as an example. You often hear the line that unfettered capitalism leads to competition which brings prices down and quality up.
But what actually happens in reality is that you start out with, say, 100 small businesses. Through mergers, acquisitions, and attrition, you end up with 20-50 of them having been brought under one umbrella.
Now you have one big juggernaut which can negotiate better raw materials prices for itself, and therefore it can sell its products at a lower price than the others can make them for. It therefore drives the others out of business, and then you end up with a monopoly or an oligopoly if more than one conglomerate arises.
Those huge corporations can now do virtually anything they want. They control a vast percentage of the labor market for whatever skill they employ, which means they don't have to compete with the little guy on wages. They get discounts on everything they buy which means they can profit at a price point that would drive ordinary businesses out of business.
In short, you end up with Walmart.
And that applies to individual people too in a vast number of areas. The son of the billionaire will inherit dad's business. He'll go to an ivy-league school because his dad can pay his tuition and because his dad built a wing of the college's school of business which guaranteed the kid admission. The kid has already out-competed the rest of us before he was even born.
That's not automatically a terrible thing - total equality is neither possible nor particularly desirable. But when the rich then become greedy and start leveraging their vast resources to choke off what resources the rest of us have access to, it starts significantly degrading quality of life for most people.
They can lobby the state legislature to cut public transit funding, which makes it impossible for people who can't afford a car to get to work, which makes them poorer, which increases the buying power of the rich.
They can lobby the federal government to get rid of environmental regulations, which lines their pockets while giving the rest of us global warming and toxin-based medical conditions.
They can lobby the federal government to cut their taxes, which is paid for by going into massive debt, or tax increases on the non-rich, or both.
They can pay to get people sympathetic to their business interests elected to powerful positions, where those people will then bend or eliminate entirely the rules to benefit those interests. In extreme cases, this leads to war, as defense contractors get rich when the military has to buy weapons and ammunition and therefore have a vested interest in getting warmongers elected.
They can even directly hurt people - Trump is famous for not paying his contractors because his contractors know that if they sue him, he'll simply out-lawyer them until they run out of money.
They can literally get away with murder. Remember the "affluenza" case? Kid got a slap on the wrist for killing someone while driving drunk specifically and solely because his parents are rich.
Such vast inequality makes it easy for those on top to do virtually anything they wish to those on the bottom without having to face consequences.
We aren't talking about "why is it bad that my neighbor can get a Porsche when I can only afford a Chevy," we're talking about "Why can you not see that it is bad when my neighbor can spend enough money to raze my house because he wants a better view and I can't do anything to stop him because I don't have enough money?"