Bob, John, and Maria are the only three people living on the planet. Bob like drinking milk in the morning, while Maria prefers to eat honey. The problem is Maria can't go outside in the jungle every day to get some honey from the top of trees, while Bob just hates dealing with cows to get some milk. One day, Maria says “Hi Bob, I can deal with cows for you and give you milk“, Bob respond “Well Maria, that sounds like a great idea!“, Bob thinks for a moment, and he said, “Why not we trade every morning, you give me milk, I give you the honey you likes!” Maria likes the idea, and the next day Maria “works” for Bob, and Bob “works” for Maria. Everyone is happy.
On the other hand, Jhon is evil, he said to Maria “What if bob hurts you one day? what if bob stops giving you honey? what if…?“, Jhon adds “Give me 50% of your milk every morning and I will protect you“. Maria gets scarred, and she accepts the offer. John did the same thing to Bob, and bob accept the offer also. Today, Bob work, Maria work, and Jhon is the richest man on the planet.
Bob & Maria is me and you. John is the biggest financial institution in the world.