Almost every day my wall is spammed with people trying to rob my buidlings and losing every other time, because their stats are crap. But since you can just wait to collect the money till you're done robbing, the only thing they lose is some wasted stamina.
Could you please make it harder for people to use that exploit? Maybe do something like making you lose 50% of your stamina if you fail. Or force people to pick up the money while robbing, and make them unbankable till you're back at your own city again.
I'm not loosing a terrible amount of money on those people, but it's still annoying to get these messages all the time, so I hope you'll take this into consideration.