Actually it doesn't. You see, kiddo, when you put your money in the bank, the bank doesn't just keep your money in a vault. They loan your money out to other people, and these people pay interest on these loans, and the bank passes on some of this interest to you, and keeps the rest for itself as profit. That's how banks make money, and it's how you make money if you put your money in the bank.
Well yes thats how it works but that doesn't change the fact that a lot money automatically becomes a lot more money. So the gap between rich and poor can only get bigger and bigger.
Well, what does it mean to have a negative balance in the first place? It means you've spent more money than you actually own. But how can you spend money if you don't own it? The answer is that you borrow money from the bank. Now, the bank can't just give you this money for free (they're not a charity, after all), instead they have to charge you interest for it. This interest is the price you have to pay for spending money that doesn't belong to you. Do you understand now, kiddo?
The whole system of interest and debt needs to go.
But what will people do when they want to spend more money than they have at the moment? How will people buy homes if nobody will provide mortgages? How will people get an education without student loans?First of all education has to be free. No student loans. For the other stuff imagine a monetary system with built in demurrage that kicks in when you hold your money. So lets say I want to build a house and you have 1000 spare dollars. If you keep them under your pillow they will lose value. If you give them to me and I build a house I'll have to give you back 1000 in a year. That saves you from losing money and enables me to build my house. It also boosts the economy because people don't hoard money but invest it.
Let's say a factory costs more than 5 million dollars. Who will built it if nobody owns more money that that? Who will sell a factory if they can't get more than 5 million for it? If there are 100 people working at a factory for $50,000 per year, who will pay their salaries? What will the consumers buy if the factory can't make and sell more than 5 million dollars worth of product? Clearly, businesses have a very real need to own gazillions of dollars, and employees and consumers have a very real need for businesses.
Yes businesses. But businesses don't have to be owned by one person. Businesses should partly belong to all the people who work there. And to the investors of course. That gives motivation and identification to the employees. The bitcoin protocol could be very helpful in that.
I could go and issue a new coin, let's call it Facebook coin. In the initial phase I give away and sell coins to people. With the money I now have I found a company called Facebook. It belongs to all the people who own coins now. Much like a combination of stock market and crowd funding.
I know this limit of personal ownership is hard to pull off in reality because greed is the prevailing motivation for people.
Sorry, I didn't realise half of the world could eat money. That changes everything. 
You do realize that you don't have to eat your money right? You can buy stuff for it like food, water filtration systems, start micro economies, educate people and so on...