They're not being entirely untruthful, unfortunately.
There's alot of career paths, but almost all of them have more people than there are jobs available. This means a TON of contact building and social networking. I suck hard at this too, fortunately my college goes to great lengths to ensure that students know how to build a social network of contacts so that they can get jobs.
Yeu can be a brilliant artist, but yeu'll never get hired if noone knows yeur name.
It requires alot of stuff that's generally considered to be extroverted, such as being sociable. I'd suggest getting a linkedin account fast, and start keeping track of people yeu know, starting with yeur professors and instructors.
For the matter of how many 'jobs' there are, the numbers that are provided are very unrealistic unfortunately. They count "jobs" as jobs that are/were available. Think of something like a movie - a movie is made, they need posters, they need advertisements, they need paraphernalia, and so on and so forth... people do those jobs, and then... they're gone. They're not needed for that movie anymore. So those same people now move onto another job which just opened up when a video game was being worked on, and do that instead, then that job dries up, and they move elsewhere. Yeu're going to be needing to go through 2-3 jobs a year on a regular basis with different employers, and the number of jobs available is deceptive since the same group of people will be getting 2-5 jobs a year, it's not a one shot deal with job security most of the time.
There's exceptions, of course, but most of the time yeu'll be moving around alot. This means yeu need to know how to get into the next job quickly once the previous one runs out. Know yeur workers and boss; they know others in the industry and if yeu do good work, and get to know them as friends, they're far more likely to drop yeur name to a colleague who's working on something else which they need someone with yeur talents for. Knowing who to talk to, who to suck up to, and so on, is a major thing in the industry...
These aren't things that come naturally to me, I know people for a short time, rarely very well, and then just kinda drift apart from them. In this career market, yeu need to cling onto contacts for YEARS.
This's going to suck for me to get used to, and I imagine it's the same for yeu, but it has to be done. Talent and skill are only a minor part of getting work in the industry... a much larger portion is who yeu know, and how little yeu can get paid. If yeu are female, native american, handicapped, or some visable minority, the government will subsidize part of yeur wages which makes yeu more attractive to hire. Do all yeu can to find anything yeu can apply for in those regards, and so on. Yes, it sucks, but I hope this gives yeu an idea of whot yeu're getting yeurself into.
Regardless, InsatiableCuriosity is correct as well. The jobs THEMSELVES don't require all that much extroversion, it's the GETTING of the job in the first place that does.