After John Mcafee tweeted a Harvard article about the amazing anti-aging benefits of younger blood swapped into older mice, the conversation quickly mutated into the thought of human beings using this method with younger human blood. However, I didn't come across very much information about people doing it. Until I came across this website ran by Matt Agorist, a free thinking cyber expert.
https://thefreethoughtproject.com/elite-ingesting-blood-conspiracy/
Of course for the average bear, it's hard to be 100% convinced of these "conspiracy theories." However, it's not difficult to imagine that people would go crazy over the idea of living forever, even to the point of cannibalism for the super-rich elite who could afford such a...delicacy. It's hard not to believe this is happening when you look at how old some of these rich people can live to, while simultaneously watching the average Joe croak in his fifties.
If you want to increase your lifespan, look up Ray Kurzweil, the director of engineering at Google. This guy is a freak of nature futurist, who is obsessed the idea of living forever, and even explores bringing the dead back to life.