...binding energy is greatest for iron______________________
...nuclei lighter than iron are produced by fusion in stars
...nuclei heavier than iron are made in shockwave of supernova implosion
...we are all recycled star dust Link
Whatever iron has the most of, technetium lacks: all isotopes of technetium are unstable.
Whatever makes iron the most stable nucleus and all technetium so unstable is beyond my pay grade. Link I do find their diagonal juxtaposition in the Periodic Table intriguing:
It's almost like opposites attract.