An article on Salon analyzes the supposed intertwining of the druggie culture and the computer gaming culture (Thanks Aaron). It's a little amusing at appears to be based on visiting a single (or very few) lan parties.

Tom steps outside to swap Counter-Strike strategies with a few prospective teammates and light up the weed. Now it's time for stoner mayhem.
[snip]
Counter-Strike and pot are a popular combination. Other games require different drugs. The venerable Atari 2600 console is still popular for many reasons, not the least of which are pot and LSD.

There is certainly no denying that the most popular demographic for computer gamers is the well-off urban guys and college crowd. Both of which are also of course known to be at the top of the bell curve for drug use. Having probably attended 100 or so LAN events in my time all over the US and even in Canada. I can see how attending a couple of those events may skew a view. LAN parties vary absolutely wild amounts though. Of all the LAN events I've been to I can only recall 6-7 of them a involving a significant amount of drug use. The others had what you'd expect from a regular sampling of that demographic. (A few guys per 100). Had I not been to all kinds of other LAN events though those few LANs with heavier than usual drug use would have probably seriously impacted my overall view of LAN parties.

But then again, it's not like my LAN experience is really a fair sampling either. Also it does sound like things are quite a bit different in places like Thailand.