The issue isn't how hard it is, but how time consuming it is. repeating the same fight and having to buy food for every fight makes the process so tedious that it's absolutely no fun. Not to mention the battles take almost 3 minuets every time means it can take up to an hour to get 1000 coins. Having more ways to earn cash or at least upping the healing from onigiri without increasing the price would greatly reduce the unnecessarily tedious grinding. If the player leveled up it would give the fights some actual purpose other than grinding for chump change as filler content.