In gambling you only win from the start then you lose whenever you win a certain amount.
No it shouldn't unless it does contribute and cause a negative effect in your life.
Sickness is called sickness because it have a negative effects in the person bearing it, but what of you are not addicted to gambling and are just playing for dun, then it should not be considered as a sickness.
More from it, it should be considered as a good thing in your life because it makes you happy.
This kind of question can be answered by anyone with a different perspective, it is a sickness of it does negative to you and not of it doesnt