For as long as I have been playing the biggest issue in the game has glared everyone in the face for a long time yet basically gets tossed out due to the nature of the conversation.
We have a food mine, iron mine, bunch of building we never gonna use(alchemy lab cough) yet we dont have a mine that we could upgrade to mine gems for us.
You wanna stop the bleeding without losing profits there need to be more events and quests that have gem pay outs for completion. If people could earn gems easier than current system a lot less complaining would be happening here.
You people have made tons of money, making some random minthly, weekly, or even daily quest with multiple steps that allows players to work for gems should have been implemented long ago.
If you are not gonna raise the summon odds then make a way for these FTP guys to farm gems at a better rate cause the current rate is just not cutting it. Everyone in game should be able to at minimal with monthlt play earn enough gems for one ten spin a month. This would not be hard to implement at all and wouldnt break any mechanics you have in place currently as the odds dont change and waiting all month guarantees them nothing, but knowing they have that chance each month through play would definitely give them no reason to feel cheated anymore.