Indeed. The reason drug use has declined over 40 years is because the biggest age cohort of those who did the stuff are now either dead, or in their 60-70's. Many younger people of the next generations (and their parents) learned the lessons of what drug addiction means, and avoid the stuff. Others have not learned, nor will they ever.
Sadly, the USA faces a conundrum. We have created a pleasure-seeking, entertainment-addled, irresponsible society where many will indeed chase illegal drugs. We also have a massive, and expensive, welfare, medical and prison public bureaucracy in place that burdens the taxpayer by any temporary increase in addiction. As such, we are stuck - we can't afford to legalize drugs, and we can't afford to keep them illegal.
Drugs will be legalized because no amount of commerce is allowed without giving a cut to Uncle Sam. The money involved makes government types salivate.
One thing I have always wondered, why do we have to have an entire federal police agency devoted to 3 perfectly legal things...Alcohol Tobacco and Firearms???