I believe that alcohol is more of a gateway drug that weed. Alcohol seems to make you feel the effects of other drugs 10 fold. Weed on the other hand makes you relax and just not stress, and for a lot of people that's enough. I have been doing some research on this though, and it seems like for some people weed just sin't enough and those people are people who have addiction running through their families. Some users do develop a THC tolerance and for them weed may not be enough enough so going out and finding cheaper and harder drugs may be more appealing to them at that time. That is why some users take a "tolerance break" here and there.