I agree with all the above posters, the main problem is the monsters get WAY bigger armies it seems when they retrieve gold coins, so this just makes the game unwinnable.
This game is a physics UNITY game. Each 'coin' is an object. They either have to be created or destroyed. Unfortunately, the way the game works, the pouch is another object, and there is three things 'counting' the number of whatever.
I never found a good way to 'create coins' out of thin air, other than them being created using the game's create function and put into the bag. The best way to use this is to toggle the option on, drop and then pick up one coin, then toggle the option back off.
I have no idea why the game is 'unwinnable' since you can make it where the enemies cannot attack you, or that it's always daytime if you like. Then again, I went to 5 separate islands and couldn't find stones/rocks or whatever it is you need to upgrade the bases after awhile. I also didn't see what exactly else to do, other than make a ship and go to the next island.
best,
Cal