The traditional answer considering the aggregate of individual spending hails as the paradox of thrift. The typical increase in savings by the average consumer comes via reducing spending rather than from an increased income. Given level income, as one consumer spends less in order to save more, that consumer increases his personal net worth. However, the decrease in spending lowers that individual's contribution to demand. If decreased spending by half the potential spenders is offset by increased spending from the other half, then there's a break even for the overall economy. But if every spender in an economy spends 1% less in an effort to save more, then overall demand for goods and services would be diminished by roughly 1%. When supply and demand happen to be matched, that reduced demand doesn't require as many employees as before to fill the orders. The resulting layoffs mean fewer people can save thus ironically causing reduced aggregate savings from a too aggressive (or panicked) shift towards individual savings.
On the other hand, if we're talking about those million households in the unified sense of a national government, we need to look at a different aspect of the question. At that point, we can shift our focus to that first part about "gets ahead". Almost no household truly ever gets ahead by saving rather than spending in real life. Saving is how households that are already ahead maintain that being ahead. Households get ahead in the first place by spending on tools to increase income (such as job training, education for higher-wage jobs, tools for trades, goods to improve and sell, etc.). Saving foolishly can be far worse than spending wisely.
In that sense that recognizes that certain debts can increase future income by more than the debt, what's good for households can be good for nations. For a nation that's already doing great, saving could do a wonderful job of steadying the already rolling wealth. For a nation that's not doing well, investments in improving the national potential will tend to do much better. In that sense, it's just like an individual. Your high-income CEO would be wise to put enough money into safe investments that he no longer has to have his job to pay the bills and just does it for personal satisfaction. Your broke high-school graduate would be better advised to get an engineering degree on loans than to try to save up from working at a gas station or other low-wage job. A nation in steady growth (or a boom) mirrors the situation of the well-paid CEO or engineer. A nation in low growth (or recession) mirrors the situation of the low-paid laborer who can't quite afford the basic cost of living and will never be able to save up enough to make a difference without taking on debt to achieve a higher income.
Simply put: If you have a high income (strong growth), it is wise to save. If you have a low income (weak or negative growth), it is more wise to spend on increasing your income. The second paradox of thrift: for an individual or nation, you have to already be doing well before thrift makes as much sense as spending wisely.
