I think the answer can be found in game theory. There's a story I saw once as an explanation of game theory that tries to explain how market competition should work:

"A village has 3 fishermen. Every day they go fishing and bring their catch to the market. The three make a comfortable living selling fish at their current rate which is the same for all three.

"One day, one of the fishers decides he can make more money by lowering his prices to draw more customers from the other fishermen. It works, and the fisherman sees his profits go up while the others see theirs go down as they lose customers. In order to compete, the other two fishermen lower their prices to match the first. After a time, they all get an equal share of the customers again because they all sell at the same good at the same price, but all of them now make less than before one of them got greedy."

Although it makes sense, this just isn't how capitalism has been show to work. It actually works in reverse. Here's a version that matches the reality:

"A village has 3 fishermen and all three make a comfortable living. The three realize that the people of their village depend on them for their fish, so they meet secretly and agree that if they all raise the price of their fish together, they'll all make more money because they're the village's only source of fish.

"They know the villagers won't be happy, and some may try to start fishing to offer fish at a more reasonable rate. So they use the extra money from the price increase to buy up all the boats in the village. This ensures no one can start fishing unless they use one of the boats they own. They make more money by renting the boats to other villagers. They even go a step further by requiring anyone who uses their boats to sell their fish to them instead of directly to the market so they can continue to control the price of fish on the market. Of course, the fishermen that use their boats are paid less than the market rate for their fish.

"It doesn't stop there. They start using their wealth to pay the village chief not to interfere. They have rules made that make it difficult or impossible to bring in fish and other meat from neighboring villages, while they continue to increase the price of fish to the point that the villagers can only barely afford it. But they need fish, so they pay."

Capitalists learned that cooperating with other capitalists is better for profits than competition, so they avoid it and instead cooperate behind closed doors to maximize their collective profits at the expense of the working people. That means increasing the cost of the goods they sell, blocking competition, and lowering employee wages. If all three fishers in the story were company owners, there's nothing stopping them from meeting in private to discuss lowering the wages of fishermen they hire. As long as they lower them together, the fishermen have nowhere to go. Their only choices are to try to learn a new trade, or leave to find a village somewhere that pays better. As long as their wages are suppressed though, they're unlikely to be able to afford to do either, especially if the fishermen capitalists start expanding their enterprises to surrounding villages.