It would have been more wasted time had I continued after a single year. I went to my first year of college on the advice of my well-meaning parents who are old and like most old people thought it was still important, and yet they agreed with my decision to leave after the first year on an offer for a real six-figure job because there was nothing to learn that I hadn't or couldn't have learned on my own. At least one of my own professors also openly wondered why I was there at all.
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.