Tony (FX lecturer) pointed out "buying" any variable means executing at the current "level" and hope the "level" moves up. (Note a mathematician would point out an interest rate is not directly tradeable, but never mind.)
Therefore, buying an interest rate means borrowing at a (rock bottom) rate.
Wrong intuition --- "locking in the interest income stream".
Eg: Say gov bond interest is super low, we would borrow now, and hope for a rise.
Eg: Say swap rate is super low, we would lock it in -- pay fixed and lock in the floating income stream, and hope for the swap rate and floating stream both to rise.
