Why do the rich people abuse drugs more than the poor people?

Because they have no need to work, have too much money, and are seeking fulfillment unavailable to them (or simply to avoid dealing with their problems).

The "middle class" abuses alcohol for the same reasons.

...and we have much more disposable income. Its pretty simple... the rich people that run in my circles work very hard all week. Their reward is doing a weekend binge on cocaine and strippers. Its the old work hard, play hard mentality. By the time Mon rolls around again, they transform back into working functional members of society. These guys been doin it for years. It's like having a few beers on a Saturday.