It's not for fun that the capitalists refuse to exploit a growing number of workers or to carryon exploiting the old ones. They get their profit from living labor as it is devoured by the machinery of the wages system. The work of others is, for capital, the goose that lays the golden eggs. As such, capital doesn't have an interest in killing it. But capital's only religion is profit. A capitalist who doesn't make a profit is doomed to disappear. Capital doesn't give out jobs out of humanism, but because that's the way it works. And if profits are insufficient, it lays off, it cuts jobs. Profit is the alpha and omega of the capitalist bible.
profits fall, and because profits fall, capitalists cut jobs. Unemployment only diminishes when profits grow again. But, as we can see from these curves, the number of unemployed never goes back to its previous levels. Periods of higher employment are only a respite in a general tendency towards the increase in unemployment.