According to me if anything that will have value and bet instead of money then it is consider as a gambling. Not only money is used for gambling nowadays, gambling can also be done with various valuable things. Moreover, even if you earn free money and gamble with that money, it is also gambling. In this regard you may have been earning money for free but it was later treated as your money. If you don't think it as your money, you might not think of it as gambling. But I would totally compare it to gambling.
Yes, if you're risky, anything to get more is gambling, but in the case of the OP, it isn't.
I recently opened an account there; I haven't done it myself, but if I understand Op correctly, which I believe I did, you're not risking anything at all, therefore it should not be considered gambling.
I can confidently describe a site where you're requested to put something other than money (sorry, but I can't think of any non-monetary object that can be used to bet at the moment) as gambling, but I don't think superpicks.com counts as gambling in this contest.
As others have stated, the only thing this can lead to is you becoming addicted to it, and eventually you'll start using real money, and that's when they'll start making money off of you, and because it's free, it'll be easier to become addicted to it, whereas when you're using your money, you have to be cautious of how much you've spent.