Once you get to a certain point...it's a cash grab. You can either spend the next year slowly gaining resources to level up, or you can spend money... There are not enough resources to obtain to level all the characters you get and they become scarce quickly around stage 13. Then instead of getting actual resources, you get pieces of them, having to collect 50 and 100 of the same piece to get that one resource... Times that by 10 to 15 for each character toy need to acend. It's madness.