Here's why you have to be an idiot to jump out of a moving train for no good reason, as (visually) explained by an idiot jumping out of a moving train for no good reason.
This teenage moron is seen here in Melbourne's Watergardens station, immediately bashing himself into the concrete as his buddies cackle away.
In the following CCTV video released by the cops, the kid stumbles to his feet after skidding along the concrete for a while.
You can see an interview with the 17-year-old dingus in question right here, where he explains that jumping out of a train at an estimated 40 km/h (25 mph) is "stupid and ridiculous." In the interview, you can see he's only banged up and not seriously injured.
So now you know what happens when you jump out of a train coming into a station: you're gonna fall on your ass and it's gonna hurt like a bitch. Mystery solved.