They ask thee concerning wine and gambling. Say, ''In them is great sin and some profit, for men; but the sin is greater than the profit.'' They ask thee how much they are to spend; say: ''What is beyond your needs.''. Thus Allah make clear to you His signs; in order that ye may consider—-[2:219]
As Arabs were used to wine drinking and gambling in the pre-Islamic era, hence with the advent of Islam, questions on these age old habits cropped up. Wine [Khamr in Quranic idiom] may not include only the fermented liquor but by analogy any intoxicating substance including drugs producing a similar effect. That there could be a beneficial effect as borne by scientific evidence, in measured doses, limited to the extent of not producing an intoxicating effect, is not denied. The prescribed limits are very much in vogue, as far as the medicinal value is concerned.
Alcohol, as such is a natural biochemical substance, hence related to live forms. In excess of the natural level in human body, it constitutes an abuse, much like nicotine. We may not abuse nature by disturbing the natural markers [alluding to normal level in body]. Fiddling with natural markers sets in acquired markers [setting in a level in excess of natural level]. Acquired markers are habit forming as urge develops to drink in order to maintain the acquired level, leading to alcoholic consumption–alcoholism, which is a sin, the price to be paid for abusing nature.
In gambling [Maysir in Quranic idiom] any presumed gain is ill-acquired, as no effort has been invested to acquire it, hence the saying that gambler is ever a loser. Pre-Islamic Arabs used to cast lots, much like modern lottery. It was forbidden, respecting the Islamic guideline on investing effort to acquire gains.
On spending, anything beyond need should be invested in right cause–charity, promoting production, generating employment, in hoarding the loss is material as well as spiritual.