There’s a reason second-year students are called sophomores. It’s a compound with the same roots as “sophisticated” and “moron”. It literally means “learned idiot”. It’s referring to the students who have a year of schooling under their belt, and think that they understand everything about the world. It’s basically referring to the Dunning-Krueger Effect, where people who know very little about something are the most likely to overestimate their knowledge on the topic.