Never mind that the illegality of marijuana hyperinflates its profits and channels those profits into criminal and terrorist hands. Pot smokers are slobs!
Unfortunately, you repeat the [academic] assumptions that are not supported by any reasonable statistics, even from pro-legalizing groups (unless cherry-picked in an apples-to-oranges fashion, the same way the U.S. anti-gun groups use their "statistics" and "polls" comparing to "gun-controlled" European countries to sway the population) and have not borne in practice where tried (e.g., Netherlands, where it's de facto decriminalized, regulated, taxed and is legally sold in their "coffee shoppes") and have no relationship to reality.
Not to make this a long post, complete with facts and tables refuting your assumptions, for which you had no empirical basis, but just a few points to yet again refute the above arguments:
Legalization of marijuana in Netherlands (as so-called class D "soft drugs" which are "tolerated" as opposed to "unacceptable risks" class A/B "hard drugs" such as heroin, cocaine, ecstasy/"X", PCP etc.) had no effect of lowering the prices or reducing the illegal drug trade in both marijuana (to those who are otherwise ineligible) or the "hard drugs". Even most serious pro-marijuana groups acknowledge these facts, however some are trying to compare selected numbers to the U.S. "illegal marijuana scenario" rather than to their pre- Opium Acts Directive years or their European neighbors where the weed has long been and still is illegal, or to more homogeneous [than the U.S.} societies such as Japan.
For example, just one study by these groups, acknowledged that: ..... After the closures, most of the young cannabis users still got their cannabis through friends who buy it at coffee shops, so the measures did not seem to have much effect on the availability of cannabis. ... After the closure of all the coffee shops in Roosendaal/Bergen-op-Zoom the number of foreign drug tourists diminished with 90 per cent. The reported coffee shop related public nuisance diminished with more than 20 per cent. ... However, part of the illegal drugs market remained and is still dealing with foreigners..." [Roosendaal en Bergen-op-Zoom is on the Netherland's border] < snip > ..... "On 1 June 2009 16 coffee shops were closed in Rotterdam, because they were located too close to secondary schools and schools for vocational training. Research showed that in areas where coffee shops were closed, there was a decrease both in the occurrence of nuisance (from 58 per cent to 42 per cent) and in the experienced public nuisance (for example: experienced traffic nuisance decreased in areas with closed coffee shops from 51% to 36 % and remained the same in areas were coffee shop had stayed). The respondents had the impression that the supply of cannabis from illegal selling points had also decreased since the closure of the 16 coffee shops. ..... < snip >
In fact, there is clear evidence that marijuana in Netherlands has become stronger, on average (higher percentage of THC content) than has been before decriminalization and than in neighboring "illegal" European countries, as well as relative to the average sold and consumed in the U.S.
From Strains of Dutch marijuana deemed to be on a par with heroin - In Holland Now, 2013 February 08
Did you know that 75% of Dutch-sold marijuana is home-grown within the Netherlands? Most of this Dutch marijuana has a 15 to 18% THC content. They are trying to 'weed out' the stronger strains out of the coffee shops. However, according to Mark Josemans, spokesman for the Maastricht coffee shop owners association in an interview with De Volkskrant, this will probably not have a terribly significant impact on the tourist industry because it is the weaker weed that is found in coffee shops and the stronger weed that is found on the street. ..... < snip > ..... This past Monday, 19th of November, justice minister Ivo Opstelten announced at a cabinet meeting that stronger strains of cannabis may become classified as Class A drugs alongside cocaine or heroine. If THC, the active ingredient in marijuana is above 15% then it will be deemed a Class A drug. A definitive date for this restriction has not been decided, but it is not likely to be set for this year, according to RTL news.
Also, take a look at California where the sham of "medical" marijuana trade has been in effect for many (?) years now. Many municipalities there have passed ordinances banning or severely limiting the "green prescription" dispensaries due to rising crime and legal costs they are experiencing.
So, do you really think that "new" enforcement and regulations will in any way diminish the power of the state or make it cheaper for taxpayers or reduce the crime or lead to better, more enlightened citizenship?
Re "channels those profits into criminal and terrorist hands" - it is one of the weakest and more dishonest arguments one can make about marijuana legalization.
First, there is not that much profit margin in the distribution chain of marijuana for criminals or terrorists to bother with it, as opposed to class A opioid trade (opium / morphine, cocaine etc.) and/or [semi-]synthetic drugs such as MDMA/ecstasy or many LSD-like derivatives.
Second, following the above logic of "depriving" the criminals and terrorists of illicit profits on drugs, should we then legalize/decriminalize class A/B and derivative drugs because that is supposedly the best and least expensive way of doing it?
I suggest, in the future, libertarians think things through and few steps ahead a little bit, before they trap themselves with such arguments.