Longevity enthusiasts are willing to pay a lot of money to slow or reverse ageing from the inside-out which is why the global longevity economy is expected to reach $17 trillion (€15.47 trillion) by 2050. One such enthusiast turned fanatic is Bryan Johnson, a keynote speaker at Dublin’s recent Longevity Summit. He is a 46-year-old tech entrepreneur who has spent in excess of $4 million in pursuit of extending his own life. He claims he is successfully controlling his biological age and describes himself as “that crazy guy trying not to die”. His regime consists of taking over 100 pills…