Do I owe this employer professional courtesy?

[JaBlue]

I befriended a kid at chess club in the city. I then became friends with his dad and somehow his work came up and he said that he had summer positions available at his portfolio management. We talked and arranged an agreement where I would come to work for him where I would do some grunt work and learn about the field in return. I would also get paid a little bit, but probably not more than minimum wage.

For the summer I worked for this office doing everything from filing to writing and designing fixed income reports for the more needy clients. This was a huge pain in the ass because I had to look up all of their fixed income holdings and write up a schedule of what they would receive each month and when the principal would be paid for the next 5 years. This doesn't sound too bad but with many clients with many millions of dollars and tons of different holdings, it really sucks. Anyway, I do crap work like this most of the time and get in on some meetings and learn some basic stuff, which is mostly procedural, uninteresting, and unhelpful to me.

I had talks with my boss who was very nice with me and repeatedly promised that I would learn more. At that point I thought I was interested in this field and stock valuation, etc. so I was excited about the opportunity. However, projects frequently came up that had to be done immediately and the learning part of the agreement was never fulfilled in my opinion.

Anyway, after I worked full time in the sumemr like this, I worked half days while in school for a couple weeks. I had one more discussion with him during the school year about my need to learn (because obviously 5$/hr is not enough to be paid for this crap, especially when you consider that after BART every day it works out to ~4/hr) to do this job. Another project came up and I basically decided it wasn't worth the hassle and quit.

By quit I mean that I stopped showing up. I felt that I didn't owe this bastard any professional courtesy because he did not live up to his end of our agreement, and in effect, wasted my summer. Do I owe him the courtesy of showing up and telling him face to face that I quit?