Kurzgesagt didn't invent the concept of disassembling Mercury to build a Dyson swarm. Stuart Armstrong proposed it in a lecture in 2012[0].

[0]: https://youtu.be/zQTfuI-9jIo?si=3jwmhoB7zx6rclhb

Pretty sure the idea predates that lecture, it appears in Charles Stross' novel Accelerando from 2005 (which is based on short stories that were published years earlier).