DeFi has become a trend because people are starting to realize that Defi can become a global alternative for every financial service used today.
For example savings, loans, trade, insurance and others. all available on blokchain and managed automatically using smart contract, anyone in the world using only a smartphone and an internet connection can access it.
Moreover, investors have noticed that in long term they're pretty good and Defi is around crypto market for a pretty long time now.
So it has potential and resources to become the next great thing in payment/banking/loans/global transactions and etc etc