Studies show that if you smoke pot, you're more likely to try things like crystal meth or cocaine or heroin. Same with alcohol. If you're drunk, you're more likely to do other drugs. Many people see alcohol and pot as less dangerous and harmful than other drugs, but the truth is, they're just as dangerous as any other drug-in more ways than one. So if you're thinking they're not as serious, get over it.
Gateway drugs work in two major ways.
Gateway drugs break down a psychological barrier against doing other drugs. Once you've crossed the line with a gateway drug, you're more likely to go there with other drugs, too. Gateway drugs impair your judgement. If you're drunk or high, it's easier to say yes to cocaine or whatever else is around. These drugs break down your inhibitions, so you're more susceptible to peer pressure or experimenting.