Well, if you are using a part of your 30% savings for gambling then it is still better but as @inanilujimi mentioned that he is depositing a maximum of 20% of his savings then I think that's bad.
20% of savings is a big deal. For an middle class person 20% savings will buy him food for the entire month for his family.
Again, that depends on person to person but for me I would never gamble more than 10% of my savings.
So that's my threshold limit in gambling.
Everyone gets different monthly income, so to allocate tens of percent for gambling, I think they have arranged for other things so that 30% is enough for them, some say this is big, so it really depends on them to allocate it.
I myself am not really sure what percentage for gambling sometimes I don't count it but I don't want to get stuck so for gambling games I think about whether other needs have been met if the remaining money can be used to enjoy gambling.
Gambling thresholds must be applied otherwise we will have an excess of what is used in gambling because it is not felt if there is no threshold.