Obviously no one is saying vegans live forever. It's not what this is about. Even if we all die eventually, why not have the best quality if life possible and have as few health problems possible, if any at all?
That's not what's disputed here though. That a vegan diet is the best way to achieve that, is.
Well, you now get all subtle on us, whereas a few comments before you summed consuming meat as "eat death, get death".
Turns out there's not a single concept as a "non vegan diet" either. It doesn't mean one gorges on huge steaks all day, or one doesn't have a perfectly healthy and balanced diet.