Why does this game keep asking you to purchase more Power-Ups? 
As of this writing? I have 47 in my inventory!. Why can’t I just play until I run out; And then purchase more?. The amount of Gems you use to buy them isn’t worth it 
Because you need different ones for different levels, so depending on whether you are playing a 1000 game or 500,000 you may be short of the ones needed for that level. Hope that makes sense.