In a depression, people will work for what ever they can get and are easily exploited. They are just trying to feed their families and are desperate for work. This need to work starts the wheel spinning again. People once again have little material goods and are in need of work. Jobs begin to open up as people once again begin to consume.
People making money just after a depression, tend to save.
There are many question we can ask about capitalism. Many go unanswered, but I am interested in how much capitalism is needed to sustain a society. It has been proven that capitalism produces wealth, but that wealth is generally ill-distributed. This is what's responsible for capitalism's failure again and again. The more you push it, The more it all falls down.