Piggy is a gambling site? It seem not a gambling site
No it is not a gambling platform. It is basically a piggy bank for for your savings whose keys are not in your hands.
nobody is going to trust you enough to send his coins to your service.
Yeah, I agree they need to build trust first. But it is an chicken egg problem lol. I suggest to take help of some reputable campaign manager and start signature campaigns. You (piggy) can also sponsor some community exclusive contests to boost your branding and credibility.