Yikes. You had a few adjunct professors who worked at think tanks, and from that you deduce that it doesn't matter how little adjuncts get paid, since this isn't supposed to be their only job? Jesus Jumping Christ.

And you know how long it takes to teach three classes a week? The in-class time will be about 10 hours. Office hours will add a few hours a week. Student e-mails another 2 hours per week. So we're at around 15 hours per week. Now, let's imagine it is a writing intensive course, which adjuncts are usually forced to teach. So, each of your 75 students (3 classes of 25) will write 5K words. So, each semester (15 weeks) you get to grade 375K words. At 300 words per page, that ends up being 1,250 pages. I'll be generous and say 1000 pages per semester. Divide that by 15, and you 66 pages per week of grading on average. Now, let's say it takes you 3 minutes to fairly read and grade a page of writing. So, you add over 3 hours of grading per week. We are now up to at least 18 hours per week.

Now, let's say you've taught this class before. This means you can (if you care about teaching) prep for each hour of class with one hour of prep. This adds 10 more hours, and we are up to 28-30 hours per week. For each class you haven't taught before, you can expect that it will take 3-5 hours of prep for each hour of class. So one class like that would make your prep time go from 10 hours per week for three classes to 18 hours. You're now up to 36-38 hours per week.

This is just to satisfy your bare minimum teaching requirements. You aren't keeping up with the latest research and articles in your field. You aren't trying to improve your teaching. You aren't going to conferences or publishing. You aren't doing your own research. You are just doing what is required to keep your job. You're also making between 19 and 23K (depending on how much you get in Summer teaching). And you're working almost full-time.

So, to work at a "think tank" you have to be able to work two full-time jobs. You have to find a think tank that allows you to do your work during non-business hours, so you can do your teaching 5 days a week. You also have to account for the fact that your grading isn't spread out equally, but that you will have some weeks where you grade 20+ hours. Can your think tank job accommodate this? Can you all but take a few weeks off to grade?

No. Adjuncts are all but slave labor. They are highly educated and well-trained academics who are being forced to do grunt work at our universities for fast food level pay.