Oh my God. No offense you’re just trolling now if you don’t know that down is meant to retain heat and stop convection. They literally molt them in the summer to keep from overheating. Good lord.

https://bedroomsandmore.com/blog/down-vs-wool-bedding-which-is-better/

“Down is not super breathable and loses its loft when wet”

https://www.switchbacktravel.com/down-vs-synthetic-insulation