Yes. Both Ardyn and Bahamut tell the story at the end of Chapter 13. Ardyn was a mortal, a healer who absorbed many Daemons inside his soul to spare millions of lives. However, as a side effect of absorbing the Daemons, he became immortal, completely unable to die.
Noctis' ancestor started a smearing campaign against Ardyn and they stole his right to the throne. Ardyn was rejected by the Crystal and the gods, and was denied the throne even after all the good he did.
Also remember, the entirety of the Crystal's light/power was absorbed into the Ring of the Lucii. And what happens at the end? The Crystal's power is spent and the ring shatters. No more Crystal.