Signature campaign earnings that I received are being hodl in the account. I don't use it cause I prefer it to be the money for my emergency needs. I will only convert it to USD if I really need it, and if I need something which is essential to my life as a student, I use my other jobs earnings.
I don't think you will be forced to bet the money you make from a signature campaign on gambling. However, sometime someone is very inconsistent with his method, because he is too close to gambling advertisement, so that sometime he also intend to double his money by gambling. It is normal human nature because they can never get enough of what they get.
If you just want to use all the money you currently have for your daily need and education, then don't gamble and may not be interested in gambling. That is the best advice for you I think.
No company are forcing their signature campaign participants to bet or gamble on their sites as their job is to advertise and promote the company they've joined on. But still if you don't have any necessary things and have some extra coins, then there's nothing wrong if you gamble and bet it on the site.
You may be able to double or even more your signature earnings if gambled it and worst comes to worst is you'll lose that earnings that came from the gambling site.
Anyway, there's nothing wrong whether you save it, trade it, gamble it or even give it to someone as you've earned it and it's your own money. Also, it's a great thing that the signature campaign helps you provide financial support for your academics and studies.