Worth is related to Equity. Stock is a type of Equity. Stock can be Risky. Surgery can be Risky. 
Reward is related to Win. Win is related to Fortune. Fortune is related to Luck. 
Worth <--RelatedTo--> Equity <--IsA-- Stock --HasProperty--> Risky <--HasProperty-- Surgery 
Reward <--RelatedTo--> Win <--RelatedTo--> Fortune <--RelatedTo--> Luck 