I don't think you can blame them for this. How many resources do you use without voluntarily paying extra above your legal requirements? Do you donate every time you go to free libraries, museums, parks, cathedrals, etc? I certainly don't and I don't think that makes me "the parasite class".
On the one hand I like the sentiment of paying for open source software. But on the other hand the free part of free software is kind of very on the nose.
This is hard though. You present commercial license, and you'll cut out a good 80-90% of the potential users, which means the OSS project is way more likely to die.
I think CTOs should be okay with allowing their employees to contribute to projects they use. In my first hand experience, they're more likely to say "no we shouldn't". It's unfair really.
This is the same argument as "capital flight". It's a bad one as most opensource isn't used commercially. There are thousands of projects maybe millions of projects out there not found anywhere in commercial projects. Most aren't written to end up being used commercially either, but if they ever are, they should get paid.
Arguing against adding a line to get paid in case it's used commercially, is as bad an argument as taxing the rich "because one day I might be rich".
You hope the idea that "commerical companies that have profited off of FOSS feel compelled and pledge to contribute to the maintainence and development of those projects" doesn't catch on?