You have to put them into the bankroll to earn profit from staking. And then you risk losing coins to winning players.
The rewards from staking almost always outweigh the losses to lucky players, but there is a chance you'll lose some CLAMs.
It means we only risk losing coins to lucky players, but won't gaining coins from unlucky players?
No. You also gain coins when players lose.
Is it possible you give us an option for staking only, or allow us putting for example 90% for staking and 10% for bankroll?
Yes. If you want to stake only you can run your own local wallet. Then you avoid the commission fee as well.
Not to be rude... FreeBitcoins will be offering a staking only option for people who want to be involved with CLAM staking, but are a bit timid about running their own wallet and don't want to take the risk verse players.
This will also fix the CLAM SPAM issue that FreeBitcoins is causing too.
(I'm not sure when this will actually happen, but it is coming after our next feature is released)
I still believe it is going to be more profitable to stake at JD than with FB though.