It's an interesting question - and yes, we do seem to spend a lot of time and energy on finding ways to get smashed.

Curiousity and freebies in high school and college. Want a hit? Want a toke? Want a taste? Want a line? Been hearing that forever - can start with peer pressure and experimentation. Been there done that.

There is plenty of evidence of ancient humans engaging in drug use.
Personally, since curiosity is normal human behavior, it seems reasonable that
many humans would engage in casual experimentation with drugs.
Some humans will also abuse them, and become addicted.
It's just how we are. We'll do drugs, drink too much, work too hard, gamble
too much, etc, etc, ad infinitum.

Some animals like to get drunk, too. ?