The 65-year-old, who battled addictions to alcohol and cocaine until 1990, said that he wishes he had become clean sooner so he could fully enjoy his early career.
He told Matt Lauer on the Today show: "I wasted such a big part of my life. I was a drug addict and self-absorbed. You know, I was having people die right, left, and centre around me, friends.
"And yet I didn't stop the life that I had, which is the terrible thing about addiction. It's that - you know, it's that bad of a disease."
John, who suffered an overdose in 1975, previously revealed on Piers Morgan's Life Stories that he would turn blue from epileptic seizures after using cocaine, then snort more when he came round.
"I never considered myself a drug addict," he said in December 2010. "I thought drug addicts were people who stuck needles in their arms - and I was the biggest junkie there was. I came very close to dying. I'd have an epileptic seizure and turn blue and people would find me on the floor and put me to bed, and then 40 minutes later I'd be snorting another line.
"It was fun in the early days because I thought, being shy, that cocaine, because it made me talk, was the key - 'I can talk now, I can be one of the gang, I can fit in'. I lost all my friends and the people that loved me didn't want to know me. My mother left the country."
John's interview with Lauer is expected to air on Today next week.
Listen to 'Sad' by Elton vs Pnau below: