To take the plunge means to commit oneself to a course of action that is very risky or challenging, but there was obstacle for him to do something very safe and secure and not very risky and dangerous in this context.
Consider the statement "There was the obstacle for him to do something very safe and secure and satisfy his curiosity.". Is the statement "There was the obstacle for him to take the plunge and satisfy his curiosity." false? Yes/no/unknown