That's how I felt about that professor. He's sparked interest in a new to me topic. As for the waste of money, I'm not certain how the university system works outside of Canada, but here at UToronto, after you've picked 3 or more courses, the fees for the term become flat, i.e. you can pick 4 or 7 courses, and the total is the same. I personally think taking 5 purely major related courses at a university with so many potential topics of interest to explore is complete madness, so the flat fee system works quite well, IMO.
Even if it ends up costing you more than you'd like, in case of a student loan exceeding $7,000 annually, the Canadian Government forgives anything above that amount, which is great if one is living alone and has to pay rent and bills.
Add to that all the possible term grants you can obtain, based on your marks, or in case of me, a low income, and it starts to make more sense to explore things a bit while at university.
While a bit off topic, I just wanted to justify taking seemingly unrelated courses for personal and not necessarily career related gain under the current education system.