I think need against when gambling platform change suddenly with their term of service actually make difficult for user withdrawing their fund with huge amount.
I'm not sure I'm getting this right but are you suggesting that casinos can change their terms of service (rules) any time they want?! If this is what you meant then let me tell you this is not true. Any reliable service will notify its customers about the slightest change they may introduce to the ToS. Besides, any change should not have any retroactive effect. Any service which doesn't follow those basic rules is to be avoided.