And if there are not enough people with disposable income to purchase the item/service being produced then the person with money isn't going to waste time hiring anyone. When income gets overly concentrated at the top you necessarily have less than optimum spending going on in the economy by virtue of the marginal propensity to consume.
Or more realistically the item’s cost structure prevents the item from being sold profitably at a market clearing price. Cost structures are in the modern world largely set by government interference in the market by things like the minimum wage which sets labor costs at an above market rate and makes it difficult to find profitable market clearing prices.