In The Amazing Spider-Man 2 is it the spider venom itself that turns Harry into The Goblin or does the venom ramp up his disorder, revealing (early on) the final stages of their family disease? His father looked the same way on his death bed.
In other words, is The Goblin the final stage of the disease or a side effect of the venom?
The venom makes the disease go the it's final stages, just like his father was before he dies. But Harry entered the Green Goblin suit just before dying, which restored his health and cured him.
The wiki explains:
The venom accelerates Harry's illness and transforms him into a goblin-like creature, but the suit's built-in emergency protocol restores his health and cures his disease.
The cure was never meant to work for the Osborns. Peter's father had added the dependency of his lineage on the venoms, a reason the bite from spiders only help Peter. As indicated in question, it furthered Osborn's weakness into the Goblin. That of course is again shown to be brought down during the credits.
