|laziness, impatience, and hubris|
I highlighted the second 'f' to indicate which letter was the silent one. This was an attempt to be consistent with other examples appearing on the list.
Source: "The final ⟨fe⟩ in giraffe gives a clue to the second-syllable stress, where *giraf might suggest initial-stress."
I was, admittedly, referring to the American-English pronunciation wherein I have yet to ever hear "hay-penny" but instead hear something closer to "haff-penny". Based on that experience the 'l' is dubiously silent.
I will not be lured into a test of yellow arcs regarding American vs. British usage of a commonly misunderstood language however. Let us instead both smirk at how odd we appear to each other & move on, enriched by the knowledge.
Wait! This isn't a Parachute, this is a Backpack!