[tcdent]

Consuming any substance really comes down to one thing:

Do you want to "feel" yourself more, or do you want to feel yourself less?

Many people are not interested (or ready) to feel themselves more. And when they do, they might not like what they find.

[MyOutfitIsVague]

That's pretty simplistic, and doesn't come close to explaining the complex interactions of drugs. Caffeine, Zoloft, LSD, Meth, Heroin, and PCP all have wildly different effects that can't be boiled down to "feeling yourself".