The gateway drug theory is a load of nonsense and has been disproved countless times since it was invented.
As Maia Szalavitz wrote in Time Magazine:
"Hell’s Angels motorcycle gang members are probably more 104 times more likely to have ridden a bicycle as a kid than those who don’t become Hell’s Angels, but that doesn’t mean that riding a two-wheeler is a “gateway” to joining a motorcycle gang. It simply means that most people ride bikes and the kind of people who don’t are highly unlikely to ever ride a motorcycle."
Countless studies have failed to prove that it is a gateway drug, and it can be disproved pretty easily. For example, in 2009, 2.3 million people reported trying pot while 617,000 who tried cocaine and 180,000 who tried heroin. There is little to no link, scientifically, or statistically.
The reason people smoke pot is not always because of the medical benefits - obviously. People smoke pot because it makes you feel great - and when compared to the harmful effects of alcohol, it is vastly superior for altering a state of consciousness - something human beings have been doing since the inception of the species.
People overanalzye and overthink marijuana too much. It's for fun. Millions and millions of people smoke pot and never get addicted any more than the millions of people who take low-potency cocaine in the form of a few cups of coffee in the morning (another drug we apparently don't have a problem with).
People who say that it's a gateway drug, NO, ALCOHOL IS A GATEWAY DRUG. In fact alcohol is encouraged unlike marijuana and the only reason marijuana isn't encouraged is because it's "illegal". Sure it can be harmful to the lungs if taken excessively, but so can be just about anything: chocolate, coffee, fat, oil AND SALAD. Of course medical benefits are worth mentioning as well as the calmness that ensures as one consumes it.
Marijuana not only has contained 30% more THC in the past few years than ever before; but marijuana is a gateway drug. If drugs only have a negative influence (such as cannabis), then why make it legal. One could argue that marijuana can calm those it extreme pain, but their are so many alternatives that can be measured.