I've drank for like 4 days straight then quit for a month!
That isn't long enough to develop an addiction. People don't drink for a week then suddenly they are addicts. It takes time and is often a slow process that people don't realize is even happening. I have seen many people become addicted and I have talked to a lot of addicts when volunteering with suicidal people. One guy I can single out as a prime example.
He was 26 , never drank alcohol his whole life. Attending college he went out with friends one night, got drunk his first time, made him sick , he swore it off. Few weeks later he does it again, just one night, stays clear of alcohol for a couple weeks. Later in the year he starts to go out with friends two times a week, then three, then four. Before he is aware what is happening his grades fall and he realizes he needs to stop drinking. So he goes back to studying but by now the alcohol effects have physically remapped his brain , thought processes are no longer the same as before he started using alcohol. His values change to where he honestly sees school or alcohol as being equal on what he should do with his life. Friends asking him on to go drink tips the scale towards alcohol vs studying and being alone in the room.
It is no longer a concious choice of what is more healthy because his viewpoint on the world has been distrorted. He cannot see it clearly on his own.
They use mice to study addiction because mice have a similar brain structure to humans. In mice they use they set it up so the mouse can have as much cocaine as it wants by just triggering a release. They start off really slow using once a day, but within a week are dead from overdose. When they examined the brain of the mouse they found that the part of the brain the dorsal fronto-median cortex was damaged. That is the part of the brain that stops you from doing something. It is what tells you to stop when you think of doing something like putting your hand in fire or running out in front of a car. Without it any thought you have, you think is a good idea.
The only way you are immune to addiction is if you don't have a human brain. You just haven't been exposed to the right stimulus.