Endless Roulette

So I have played Raid Rush for 104 days straight, never missed a day of watching an ad to play endless roulette. I have only received green and blue cards for skills and towers, other than a single time I received 200 gems. Is my luck this bad or is the rng of this game just geared towards handing out literally zero rewards for the effort? Anyone else actually get anything from playing roulette? It feels like playing for 75 gems would be such a scam, although maybe you actually get better rewards if you do?