This game is about maths and numbers... :) just few numbers...

lvl 80+(i have lvl 83, maybe higher lvl can have higher cap) can gain 63 600 moon scrolls per week

63 600*4(weeks) = 254 400

Cave event need 1050 Cave keys, 1050*200(key price) = 210 000

You c*e 44 000 moon scrolls for another items, or can buy more cave keys, your choice :)