The calculation is that of course there are defences, but if you have a big stockpile of $20K drones, and your opponent has a limited number of $2mil drone interceptors, then you can keep throwing drones and keeping your opponent busy there, and you're coming out ahead even before one finally gets through.

See: https://bsky.app/profile/mekka.mekka-tech.com/post/3mgrvx5gr...