Conclusion number two: If Hollywood was more scientific, most movies would end after the first 20 minutes because their heroes would just die in some dumb way.

Though this films / shows does not end in 20 minutes. I think the best / competent characters (at the start) dies due to bad luck (Got hit by a sniper, got hit by a mortar, got trapped in an avalanche). Might be a bit morbid but at least most of I posted here more or less has a happy ending (Well in the war movies if you are anti us then probably not a happy ending :p).

Alive (1993 film) - Wikipedia
Band of Brothers (miniseries) - Wikipedia
The Pacific (miniseries) - Wikipedia

Its a bit of a cheat as this stories are based on real life so Hollywood cant to get too artistic on making the film/show.