What underlying cause leads to the economic crises described in Marxist theory, where production exceeds consumption?

In Marxist theory, an economic crisis often happens when production exceeds consumption because of the way capitalism works. Capitalists produce goods to make a profit, but they focus on producing more and more without considering whether people can actually buy what they make. This leads to a situation where there are too many goods and not enough buyers, causing businesses to lose money and sometimes even fail. For example, if a factory makes a lot of shoes but people can't afford to buy them, the factory might have to close, which then leads to job losses and even less money circulating in the economy. This cycle of overproduction and underconsumption can create tension between different classes, as workers lose their jobs and capitalists struggle to maintain their profits, leading to potential conflicts and calls for change.