Drugs are a necessity...

...as a socio-evolutionary regulator. 

Think about it. 

In any given situation, if one person gains a slight advantage over others, he will attempt to further that advantage. Like wishing for three more wishes as your third wish.

And if he has an advantage already, he will succeed. The gap widens.

Over time, one person will have all the resources, while the rest have none.

As a result, this person will have the capability to continue to hold all the resources, while the rest continue to starve.

And what happens when you have no resources? You can't have kids. Either you can't afford them, or raise them properly, or save them in dire situations.

Genetic diversity of a society starts to become completely skewed towards the one guy. Or girl, it doesn't matter.

And this is not a good thing. 

But, if there were something else that becomes accessible as a result of having all (or a lot of) resources - like money - something expensive, hard to get, but that would make you feel good, that you desire - you would try to get it. And you would succeed.

Something that others couldn't take away from them, and they could stop them if they tried. 

Something like...  a gateway drug. That leads to the harder, more dangerous stuff.

The resourceless, the impoverished, can't afford it. Only they can.

And once they're addicted, it eats away all their resources and kills them.

Balance is restored.

If you have nothing, it's just a waiting game. The person who has everything also has, inevitably, something that will destroy him.

Fast cars. Alcohol. Venereal disease. Drugs. Thrill-chasing. Fights. 

All you have to do is make sure it doesn't get you as well, accidentally.

Self-control is the greatest weapon you have, the hardest to manage and the easiest to use. 

Everything else is working with the universe to make sure genes continue to proliferate. You, the self, the consciousness, the mind inside that meat bag whose sole purpose is to act as a life-supporting vehicle for your genetic code, is an accidental, happy, short-lived coincidence. 

Enjoy it. 

Don't throw it away. 

Don't be a pawn of the Universe, a statistic, a variable like trillions of others in the great dance of life, a cog in a machine. 

Be yourself.