Why is tobacco/alcohol so addictive to the brain?

According to an article I read in the April 2007 issue of Scientific American, alcohol compensates for an imbalance of neurotransmitters in some people.

My own theory about tobacco is that the plant has evolved to perpetuate its own survival by addicting people to cultivate it. This is similar to the rabies virus, which has evolved to make animals crazy so they will bite and spread the virus.

Because it is a genetic problem, and people when they do drugs it clouds thier problems in life, making it seem easier at the time until they are off the drugs and go into withdrawl, a vicious cycle that leads to death.

well as a current smoker --47 yrs-- i can tell you that there is something in my brain that tells me to keep smoking and i will feel better........i have to keep doing it to maintain a "ok feeling" if i stop doing it i feel shitty; i am also a 25 yr iv drug addict who quit in 1983. of everything that i was addicted to the smoking is the hardest to quit. i th ink there might be some chemicals in my brain that are hay wire. all i know is i would love to be TOTALLY DRUG FREE.

because there is nothing else to do and it is very relaxing i dont care what docs say I LOVE MY TOBACCO

Why are there alcoholics?

Why are there work-a-holics?

Why are there stoners?

Why are there religious zealots?

Why are there gym bunnies?

Why are there soccer moms?