One thing that I think is really big in DeFi is the idea of permissionless composability. Let me give you an example. Say you want to start a traditional fintec

One thing that I think is really big in DeFi is the idea of permissionless composability. Let me give you an example. Say you want to start a traditional fintech company that aggregates many existing banks to provide the best interest rate to the user. So it would basically move your money around between banks depending on where the best rate is the current day. This is basically impossible to build, there is very little ability to integrate into various banks, and even if you can, you need permission to do so. However, you can build this on DeFi today quite easily (see yearn for an example), and you don't need to ask anyone for permission, you just hook things together. The smart contracts can move money around within DeFi based on algorithms that will find the best rate of return on various collateral coins. This is why people are calling it money legos. It allows rapid innovation from the edges, instead of the center, which is insanely powerful. I hope this inspires you to do more research.