Moderate is good but the higher it is the more dangerous they are. People become addicted to drugs and drink when they constantly have the high adrenaline level in their body.
That's likely the effect of gambling addiction as no gambler would just gamble all day, sometimes this addiction would not allow us to sleep since we don't have a peace of mind, therefore these addicts will try do drugs and drink so they can be calm and they'll be able to sleep when they are too drunk.
You talk like all gamblers are also alcoholics. While this may be true for most of them, I think not all are like this. There are also gamblers that know what they are doing and not losing control on anything. Not on their health, not on their finances.
It is possible to be a responsible gambler. You don't need to lose your health.