Basically your answer is like the classic "I could have got a 5.0, but I partied", which is a statement that says a number of things. 1. "I think all the kids who got 5.0 are boring and don't party" (untrue). 2. "I am not capable of getting a 5.0 and partying" (probably true).
That the person would even make the statement says something about their general level of intelligence. Hence when you say "If I had but known, I would have been in the top 100", you are saying "I had no idea that a hugely publicized course at a renowned university might lead to job opportunities". This lack of intelligence seems to contradict your first statement. Or it could be that you are not in the habit of thinking about such things. I hope you are either a kid, or an incredibly wealthy trust-fund baby living in isolation. Usually, however, I hear such remarks from people who are not smart enough to realize they are not smart enough, or they are quitters, or they are victims.
The "partying" I was doing instead of putting a non-casual effort into the class was dealing with some projects at work, and starting to read a book on analytic number theory because I'm tired of being someone who doesn't understand the proof of the prime number theorem.
> you are saying "I had no idea that a hugely publicized course at a renowned university might lead to job opportunities"
Yeah, I did not think it would lead to much in the way of job opportunities. That's because the class is just an introduction. If you compare almost any section of the class to the corresponding section in the Russell and Norvig book, you'll see that they are leaving out a lot of detail in the class. The homework in the class almost never pushes any limits of what was done in the lectures. Many of the homework problems are just things that were done in lecture with the numbers changed.
I would have expected the job opportunities to start at a deeper level than the class reaches.
Aptitude and interest goes a long way.