The systems we create today need to avoid creating crises later. Human affairs are unpredictable, but not hopelessly so. Through economics we actually can spot errors, learn from them, and plan to avoid them.
Source: The Price of Trading Future Obligations for Today's Benefits - Foundation for Economic Education
In any context, using your resources wisely and responsibly is important. When it comes to personal finances, it's important so that you don't become a burden on your family or society. When it comes to natural resources it's important so that those resources are still there for future generations, and when it comes to government spending it's important so that you are not condemning your children and future generations to the potentially impossible burden of servicing that debt.