With some crops, we don't really "need" any of it. If the United States had not produced a single grain of sugar in the past 50 years, Americans could have gotten all the sugar they wanted and at lower prices, simply by buying it on the world market for half or less of what domestic sugar costs. Sugar has been in chronic surplus on the world market for generations. It can be grown in the tropics far cheaper than it can be grown in the United States. All the land, labor, and capital that has been spent growing sugar here has been one huge waste.