Dear @detlev, of course you have a lot of cards including mining operation which is very expensive one can save some reward, but for most users like me, no way to get them and I invested on my town with normal cards and tax for me is really 90%!!
I agree with @cryptoknight12, this game is a ponzi scheme and now there are no more new users investing, they are trying to keep what whales need, the hive rewards, for us with SIM rewards no way to get anything!