Does it make sense to finish playing with a pure lich for the sake of killing 9-10 myths? (Pathfinder: Wrath of the Righteous)

RITCHII
There will be. And if you change the myth, you will lose all previously received spells and skills of the lich.

Xmax1234 I exchanged
for the Devil and for the Dragon - the spells remained ... And yes, thanks, I performed the ritual and got 3 cool 10s. But I understand that without the ritual in the ziggurat of the 9th lvl, the mythic is not available?