Again I have been asking people about the world's worst problems, and at last I have come to find someone who agrees with me, a government clerk. According to us, the world's worst problem is stupidity. Okay, so she said it was "ignorance," which only somewhat overlaps. In any case, people's lack of education and/or refusal to apply intellectual effort is a major problem that causes several others.
People not knowing any better is improving over time as education becomes less expensive, more extensive, more readily available, and more publicly funded. The libertarians like to complain about paying for other people's education, but it serves no one to have a nation of ignoramuses with no future. Especially if said ignoramus thinks that the best way to get money is to burgle your house, rob you, or run scams. (Some crime is, in a way, an industry. An industry that operates to public detriment.) If they do not do crime, they may turn to begging, which is both annoying and an eyesore. Or they abruptly die of hunger, thirst, or exposure. In any case, it will cost you money either way.
The economy especially benefits from education. Currently, the United States has a surplus of unskilled labor and a deficit of skilled labor. Companies don't want to hire people with little education because they would be too expensive to train, and people with little education also often have little money and do not feel they can afford an education, perpetuating the problem.
Little can be done about intellectual laziness other than loss of privileges and perhaps a swift slap to the back of the head. It's a social problem.