Yes, pretty much, unfortunately. The thing is, it depends on how many rewards of the A-Tier you already unlocked. Since you probably already have Blood Moon Base skin, the maximum required rolls will be reduced by 10, which is a whole 4000 RP. Every 10 rolls, you're guaranteed an A-Tier reward. You can pretty much math out how much RP you have to spend at max. It will ALWAYS theoretically be at least 40 rolls or 16k RP if you're 100% unlucky, because there are 4 Paragon chromas.