I don't know if this was suggested or not, but we should get something from doing the achievements. Most games have achievements in them, but they are not just simple badges that congratulate you for doing a certain task. Depending on the game some will give you currency, XP, or even items.

So my suggestion is that you get idk let's say 100SB for easy achievements, such as Fatality - Lost your first NPC battle and you could get 1Gb for harder achievements like Buff Baby - Have a cub born with 1,000 or more stats. And like once you complete one achievement you can go to the achievements and click "Claim" underneath to get the reward.

Achievements also have different categories like Breeding, Battling, etc. You could also get 10Gb for gaining all achievements in that category. Those are just for reference, the prize pool can vary between SB/GB or even exclusive decors and BG that you can only obtain from here.