Well, I don't know if you'll agree, but I think a purpose of a budget is to pace the amount of money that you spend and save. Everybody needs to have a certain amount of money saved in their bank account to take care of themselves when they retire, and a budget helps make that happen since you don't ending up spending almost all of your money. A budget also helps you decide how much to spend on each thing that you buy. For example, you wouldn't want to spend more on toys for your entertainment, but you would spend more on groceries to keep you healthy and alive so you don't starve.