enantiodromia

To be honest, I can barely say this name.

From Wikipedia
[Enantiodromia is the] principle introduced by psychiatrist Carl Jung that the superabundance of any force inevitably produces its opposite. It is similar to the principle of equilibrium in the natural world, in that any extreme is opposed by the system in order to restore balance. When things get to their extreme, they turn into their opposite.

The quote is from William Butler Yeats’ “The Second Coming”.