To your second question - less than a hundred, but tens. Most people who are worth listening to publish their work and their thoughts. Email is free. Experts love to answer questions about their work, professors hate doing extra work for no extra pay. The incentives here are not confusing. How much time have I taken? Confusing question. These are real people with real passion, and they answer questions with that in mind. Professors are obligated to puke up an answer. I've gotten responses in most cases, in some I haven't. When I don't get answers it's because the targets are smart and busy. If I wanted more engagement with my random questions I'd offer money, and if I had offered money every time I'd still be below par on the money I wasted on college. If I wanted to justify it - I'd say I learned enough to validate that paying real money for another 3-6 years would have been less valuable than burning it for heat.
I think you completely misunderstood this interaction.
There are 2 possible explanations.
1. You are so smart/knowledgeable that the professor thinks you are beyond college.
2. You were acting like such an arrogant know-it-all that the professor was being sarcastic.
I’ve seen #1, but I’ve seen #2 many times.
You sound like you have a huge chip on your shoulder about not having a degree. I had the same issue at one point before I went back and finished (after working as a professional developer for a while), so I recognize it.
When I did go back, I asked questions in class, I went to office hours to ask questions, and I did research projects with professors. Some back of the envelope math says it would have costs me about twice what I got out owing if I’d paid for an equal amount of time with whatever experts I could find.
My strong suspicion based on the few posts I’ve read is that your attitude is the reason you had such poor interactions with instructors.
Chip on my shoulder - no, and it's a silly label to begin with. Understanding that it's for other people who value the paper more than intrinsic understanding, yeah.
EDIT: I will concede in some way that I'm proud of not having a degree, and it does influence my thoughts on this topic. I've met some real idiots that do, and I don't consider it a serious differentiator.
Also looking up the thread - at my early jobs, I was surrounded by many people who were interested in educating me on any topic I could think of, because similarly we were all being paid for our time. The difference between that and school was the assumption that we were both motivated and capable.