The DeFi section in specific is something really new. It aims to provide financial services outside the centralized financial system (CeFi).
It began around 2017, and as of late 2021 already has amassed over USD 107 billion in locked value (value that can be used in the system).
The centralization of these financial services is harmful to the economy, as it makes their use difficult by various economic agents. As Schumpeter (the famous economist of the theory of destructive creation) pointed out, credit is essential for any growth and development in the economic arena. DeFi extends the scope of global credit reach.
In short, DeFi is more than a market eccentricity, it's a need that's coming true. Complex and easily obtainable financial services are essential to the economy.