A lot of people will exploit the bonus system, if they figure out how it is calculated. The bonus system would reward you, if you lost a lot of money during the week or the month, but the moment when you win a lot of money, it will give you a shitty reward. (It happened to me over the weekend, when I hit a 900x multiplier, just before the Weekly was paid out, and it punished me!)

So, if you play games with a higher Return to Player, your reward will be much different to when you wager with something with a lower RTP.  (Basically, the more you lose, the higher your reward) 

Stake.com still give some of the best bonusses in the industry, so people should acknowledge that and make the best of it.