forgo money - do without money or spend money on something

"A study conducted at Harvard University found that people were willing to forgo money so that their opinions would be broadcast to others. We are not talking about well-crafted insights here. These were people’s opinions regarding mundane issues, like whether coffee is better than tea. A brain-imaging scan showed that when people received the opportunity to communicate their opinions to others, their brain’s reward centre was strongly activated."

I always thought that "forgo" means "do without" that's why I first thought this sentence expresses that people are willing to do without money (accept that they don't earn anything) as long as their opinions are shared online.

After reading the paragraph multiple times, however, I got the feeling that it means users are willing to pay in order to share their opinions online.

Can "forgo money" translate to "spend money and thus do without the amount you chose to spend"

Thank you!

Your first inclination was correct, that the people were willing to participate without being compensated (better phrasing may admittedly have been that they were willing to "forgo payment").

If it were intended to say that people were actually paying to participate, that's an unnaturally awkward way to phrase the statement. If the author intended to say "people were willing to pay" it's not reasonable to think that they would unnecessarily complicate and confuse the statement by saying "forgo money" instead.

On the other hand, the original statement being "people were willing not to be paid" lends itself nicely to the more concise phrasing above.