10% from a bankroll MONTHLY is a crazy and high revenue that would beat any other profit/platform or even kind of investment (maybe investing in drugs or being a loan shark could be more profitable!) In less than one year, by coumpounding it could be easily reach... this is a crazy target!

Of course any gambler would be satifisfied with that (of course if he is not searching the crazy random numbers of high jackpot).
There are some gamblers able to reach these crazy profits.
Have a look on p2p fees that they are asking to these players (more than 40% of their wins)