Caltural Shock

I love challenges.
I love dealing with cultural shock.
I've been involved in Canada University life nearly 2 months.
There are couple of things that keep wandering in my mind.
Why they keep drinking alcohol excessively even they've been told that alcohol is not good for our body?
Luckily, I have alcohol intolerance. :)
Why they keep eating unhealthy foods even They KNOW what foods they should and should not eat?
I want to tell them or ask them, well I'm not brave enough to do that.
Can someone give me the answers?
or Why do they like Partying so MUCH?? Personally, I don't like partying...the music is too loud that can literally let you be deaf instantly, and people keep dancing and drinking, and too crowed, and sometime unexpected things happen....
I've seen people throwing up or even fainted in the toilet after drinking alcohol.
And they still drinking and drinking...