I'll take you at your word, but I hear that all the time from people on the Internet. People on the Internet seem to be immune to all the problems and consequences other people experience in real life.
I know many people who can't seem to put the weed down, which is the exact opposite of what people say on the Internet.
Be that as it may, you are correct. People are different. I don't believe everyone who smokes weed gets addicted, just like I don't believe everyone who drinks gets drunk. Some people - and I know a few of these people - have an incredible genetic capacity to drink, smoke cigarettes, eat unhealthy - and never experience the negative side effects of consequences of their action. But these cases are rare compared to the norm, which establishes why we're even talking about this issue. Shrug.