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.
Addition to this;
Especially be careful when giving your personal identity, this is something private and should not be shared in public at all. You may earn some little bucks with that but later you can face a lot of difficulties in your life.
If you rethink, all free web sites or programs collect some info from you.