The reason illegal drugs is a multi-Billion dollar business is, there is a lot of demand.
The reason alcohol is a multi-Billion dollar business is, there is a lot of demand.
So, what is the difference between alcohol and drugs?
1. It is possible to have a small to medium amount of alcohol and not get altered. It is not possible to just have a little weed and not get altered.
2. Marijuana has been proven, statistically, to be a gateway drug. That is, is has been proven that those who regularly use (not just try) marijuana go on to harder drugs far more often than those who regularly use (not just try) alcohol.
3. Moderate, consistent use of alcohol does not induce psychosis. Moderate, consistent us of marijuana frequently does.
If we all lived on our separate islands, I would not have as much of a stake in it. We don’t, though. Our society depends on a majority of sane, sober, rational adults.
Alcohol is a drug. That's like saying what's the difference between a Cadillaic and cars.
As for your points:
1. It is definitely possible to have a little amount of pot and not get altered. Much like it's possible to have a little amount of alcohol and get altered. All that is dependent on the strength and quantity of both drugs. You can drink a twelve pack of near bear that has a 0.5% alcohol volume and not feel much, much like you can smoke a pound of 0.5% THC ditchweed and not feel anything. Conversely, you could take a shot of everclear and get blasted like you can take a hit of 18% THC weed and get blasted.
2. If you have any proof that pot is a gateway drug, I'd like to see it. The stats would indicate otherwise. There are 13 million or so past month pot smokers and around 2 million and around 700k past month heroin users. Not a huge gateway. The reason more pot users go on to use other illicit drugs as opposed to alcohol users is partially from sheer volume, and because pot users are exposed to a black market that sells other drugs where alcohol users are not, in general
3. I have no idea what your definition of "frequent" is but it certainly isn't what most people use. Psychosis in general is rare, and even a 40% increase of something (if you buy that pot use is 40% more likely to increase the risk of psychosis) rare isn't frequent in my book.