Turkey’s Election - Why a Runoff?

In last Sunday’s election, President Erdogan received almost half of the vote, but not enough to be the winner - yet.  How does he hold onto power?  Turkey’s economy is in great peril and journalists are in prison while Erdogan dismantles democratic institutions.  Is Erdogan, like many other autocratic leaders, a narcissist?  Or is there more to understand about him?  And if he does prevail in the May 28 runoff, what will be the impacts on Turkish lives and global geopolitics?