The drug is very dangerous if you get hooked on it, you can not stop to use it, very harmful to your body. I think that is the mildest form of the drug marijuana, but marijuana begins after switching to something bigger, heroin, cocaine.
It's really not very dangerous and is probably one of the safest drugs you can take as it's impossible to overdose on it, though smoking it isn't exactly great for your lungs and like any drug you can get addicted to it though most can smoke it casually without any issues. The cannabis is a gateway drug theory which you allude to in your last sentence isn't true either. Tobacco and Alcohol are the true gateway drugs but it's not the drugs themselves that lead to others but people usually try these ones first before they try others.
