Well, imho, scam is not necessarily take away your money. If you give something (your time, your personal data, anything, your signature) because you are promised to be rewarded, but in the end the person/entity is breaking their promise, it might be called scam/fraud.
And BTW when you give your data freely they might sell it to some people, and many people willing to pay for personal data.
I think you you are right that being scamed is not limited only about money but also about other thing like time or whatever.
So always becareful although its just free but not all free will turn into a scam. Scam now is very often we find so i hope we will be in safe.