Casinos are not afraid of you winning their money but they are more afraid of you not betting with them. When you bet more often, you have a higher chance to lose with the house edge. This is one of the reason why casinos give you freebies to encourage you to return to bet.
Yup because of their house edge there is no fear for casinos if you win or lose and their freebies really is an attention for other players addiction is more prone because of it,