First, that's not how any of this works, and second, said gaming PC owners wouldn't take part in this experiment to save themselves first and foremost but rather to help save as many other people as possible.

Corporations are just a way to organize people doing things that people demand.

Yes, the people who are developing vaccines generally have jobs, you would not learn their craft out of the pure goodness of your heart, why should they?

If you want to help somebody develop and test a DNA vaccine for SARS-2-COV without FDA approval or perfect medical ethics, there is an option for you as well: https://youtu.be/7BTvVnOgc10