You were probably more excited that you were arrogant, but your choice of words "I'm the master" implied an attitude that your abilities were unsurpassed, to which anyone would be incredulous. It was probably that perceived attitude of arrogance that the others were reacting to, not your actual skills as they were.

To claim mastery to a group of people who have no prior experience with you seems like a result of misreading the social environment. Whether that misreading is borne of arrogance or naivety is a separate thing.

Software development classes are themselves more about learning how to socially coordinate people to complete a project with ambiguous requirements, which depends far more on social and situational awareness than raw skill in a particular technical area. So if your takeaway years later was learning how to better communicate your abilities with a team of people, perhaps you learned exactly what was intended by that class.