Even though it seems like they have more money than you, adults need to spend a lot more of it than you do. They have to buy food, groceries, maybe petrol for the car, pay bills for things like electricity and gas, and also pay rent or a mortgage so you can live in your house.
These things are called essentials – they have to be paid or you'll be left without something you really need. If there's any money left over, then it might be spent on luxuries. These are things, like toys, games and sweets. Things that you don't really need - but they can make life a lot nicer!
If you want a luxury that you can't afford right now, it's always best to wait and save up for it, so you can still pay for essentials. Otherwise, you might end up having to spend more money than you really have – which could mean you get into debt, where you owe someone else money that you eventually have to pay back.