I dont understand what insight even does.
Should I be using these madman's knowledges
It's a currency for bath messages on the side of the work shop in the hunters dream they will appear when you have ten insight, it's used to summon player with the bell, and if you have some the game will scale and also possibly populate the world with special enemies and anomalies, the amount of insight which this happens at is still kinda unknown but somewhere around 10 and 20 seems to be the case.