Every new technology has a killer app. An application that takes that technology from a novelty to a useful tool that solves a real painpoint.
For the Apple II, it was spreadsheets.
For Smartphones, it was messaging apps like Whatsapp, Snapchat, and WeChat.
For Web 2.0, it was social networks like Facebook, Twitter, and YouTube.
What will blockchain’s killer app be? How about Web 3.0? Only time will tell.