There seem to be heart issues involved in most of the energy drink related deaths. More specifically, people finding out they had heart issues, by dying.

So "those people just shouldn't drink caffeine then" would be the standard advice, except that some people apparently die before they realize that they're in that category. (It seems to be mostly young people? My country recently banned energy drinks for people under 18, they now check your age at the supermarket if you try to buy them.)

The strange thing is, if it's caused by caffeine, we'd also be hearing about people dying from having too many coffees, but you never hear about that. Maybe it's some of the other ingredients (taurine, guarana) or the combination?