Why not have it set up where there is a fee scale based on how long you keep your coins on the chipmixer system? ranging from investment return for keeping your coins on for a long period, to paying higher fee when you remove your coins immediately. something like this.
+3 months= +1-2%
2 months= +.50-1%
1 month= +.10-.50%
10 days= 0%
5 days = -0.10- -0.50%
1 day= -0.50%- -1%
immediate withdrawal to 1 day = -1- -2%
This is a very interesting idea. Now you can either withdraw your chips and receive private keys or you can take voucher to withdraw them later. Taking the voucher keeps your chips in the pool.
We could add an investment return for vouchers ie. you keep 1 BTC voucher for some time and when you redeem it you get more than 1 BTC.
The only problem I see here is that it looks exactly like pyramid-scheme. All the accountability that ChipMixer is proud of - we do not keep your funds, we give private keys immediatly - is missing from this investment idea.
Please check your PM, I have sent you 32 mBTC voucher.
Besides the pyramid scheme stuff everyone is talking about, another problem is that vouchers could be all saved up and reclaimed at the same time, and if this is done at a large scale, it is unlikely that ChipMixer is going to have enough chips to redeem the vouchers. Other than that, I do agree that it could be seen as a potential long-term scam, so maybe it is better if it is simply kept as it is. No point in playing with the trust that you have already earned and risk losing it.