People who also smoked everyday of their life while being fat that lived to be over 100. It's about putting the odds in your favor regarding risk factors. A vegetarian diet keeps your arteries clean. Your genetics ultimately determines your health. What you have control over are the risk factors.
The studies I've seen show vegans live slightly longer than meat eaters. This might not have anything to do with the not eating meat though. Vegans are also less likely to smoke, drink, eat excessively, or do illegal drugs. This probably has a lot to do with it.
What's the point of living a few months longer if you are miserable your whole life? It's all a crap shoot after 75 anyway.