Narrative economics…

… is the study of network power law effects…

… caused by clusters and the links between them…

… which can under certain conditions drive virality…

… the tipping points of which may seem random…

… but are governed by network rules, which are dynamic.
This isn’t random, just easier to explain after the fact, often when the narrative is proven false, which is called a bubble.
Financial bubbles are idea bubbles, financial markets are social networks.