The fundamental reason is because we may create financial products. They can be socially very useful, they may endow their creators with vast profits, or both. So the creation of financial products is strongly incentivized both from the buyer- and seller-sides.
However, there are only really two things that we can use to create these products: debt and risk. Thus, when we try to create financial products, we create structures composed entirely of debt and risk, which become very complex. The reason why they become so complex is similar to any other case in which you try to make highly sophisticated structures from only very simple/basic components: there ends up being a great number of details.
However, there are only really two things that we can use to create these products: debt and risk. Thus, when we try to create financial products, we create structures composed entirely of debt and risk, which become very complex. The reason why they become so complex is similar to any other case in which you try to make highly sophisticated structures from only very simple/basic components: there ends up being a great number of details.