The simple fact is that if drugs are made legal, more people will use drugs. There is no evidence of this, and the DEA didn't present any here. Slightly more than two-fifths of inmates convicted of homicide or assault committed their current offense under the influence of alcohol or of alcohol with drugs. This is a good argument against alcohol. It doesn't say much about the illegal drugs.
Alcohol is the drug with the biggest relationship to crime problems, and always has been.
Heavy alcohol use has changed little since 1985, when there were 12 million heavy drinkers. This is another good argument against alcohol, but doesn't say anything about the illegal drugs. This isn't surprising at all. It is just a reflection of the fact that people who abuse one drug are likely to abuse other drugs. This is another good argument against alcohol, but says nothing about illegal drugs.