I want to open a discussion about the existence of coins - as I see on the market nobody has coins now - or very few still have it.
As I see it, for upgrades on marble, stable, hardwood sawmills and I'm sure that many more buildings it is required to pay 100 coins/building. This money exits from the economy. The coins that enters the economy are from lvl up (100/level) and from the gold factories that are so expensive that you cannot build without first upgrading hw sawmills and marble to the max levels - with coins.
This means that soon there will be no coins in the market.
Maybe I don't see all, please correct/complete me.