Let’s assume for a moment that your job has a unique payment structure. You get paid in cash on January 1, and you will not receive any more income until next January 1. You would know intuitively that you need to plan your spending so you won’t run out of money before next January. You would probably separate the cash into “stacks” - one each for your mortgage/rent, transportation, food, electricity, clothes, charity, etc. That’s exactly what a budget is: Taking stock of your income and your obligations - planning in advance how you will save, spend, and share the funds available to you.
Everyone needs a budget, whether they have a lot of money or a little money. It’s pretty simple: you need to know how much money you have and how much you will earn in order to make smart decisions about how you will spend.