I know a decent number of people who take this stance. Honestly, I find it a tad dramatic.
Nobody is making light of the death of those people, merely pointing to the circumstances that led to it. You do realize that most of the people drank the koolaid willingly, right? Some people were shot up with the poison in their arm, etc. but the people who drank the koolaid mostly did so of their own volition. That's why the phrase exists. It's pointing to a moment in history that we should all remember and be careful not to reproduce.
"Drinking the koolaid" just means buying into something somebody is telling you without really questioning it, to me anyways.