The baby-faced singer, 16, said: “If I was at home and I wasn’t doing this, I’d wish that I was in this position.
“Now that I’m here, I sometimes wish I could just go back home and just chill.”
But Justin’s autobiography, out on Thursday, reveals his life before fame wasn’t typical.
His Canadian parents Pattie and Jeremy were in their late teens when he was born, and split when he was 10 months old. In his book First Step 2 Forever, Justin says: “When I was little, I longed for a ‘normal’ life with a ‘normal’ family.
“Mom worked her butt off at whatever job she could get to keep a roof over our heads.
“There were no luxuries but it never occurred to me that we were poor. We had each other, which was everything.”
Pattie would invite round “interesting, artsy people” to play music, and Justin taught himself the guitar and singing.
He got in extra practice after being grounded twice – once for skipping school and another time after a run-in with police.
Justin explains: “We sneaked out and went bike-riding at 2am, and the cops picked us up and took us home.
“My mom came unglued about that, and I was grounded for a few weeks but that gave me time to work on my chords and good guitar riffs.”
Justin tried to keep his love of singing quiet at school for fear of being picked on. He said: “Unfortunately for the bullies, my dad was an ex-professional fighter who used to take me to his training sessions.
“I’m not a fighter by nature but if somebody shoved me, I shoved back harder.” Justin’s first appearance on YouTube – the video website that launched him to stardom – was at a mass brawl at his school.
He said: “A bunch of people were involved and a bunch more were taking videos of it with their cellphones. Nobody got seriously hurt but the video made it look like something out of Mortal Kombat.”
The next video was him coming third at a singing contest in his home town of Stratford, Ontario.
It was posted on YouTube by Pattie, and afterwards Justin decided to try his hand at busking. He said: “Mom wasn’t sure, so she insisted on having Grandpa sit in his car across the street.
“I was hoping I’d get 20 bucks. After a couple of hours, I had almost $200. I felt like I’d discovered a gold mine. At the end of one day, there was a note in my guitar case. It was something like, ‘You’re cute! Call me! Love, Tiffany.’ And a phone number. I was 12.”
Pattie wanted him to start a college fund but Justin used the cash to take them to Disney World – their first holiday.
Videos of him busking ended up on YouTube and he was signed by a record label and mentored by R&B star Usher. Justin – worth an estimated £100million now, is touring the world – but being a mega- star is far from easy.
During one rehearsal he was left hanging 30ft above a stage when his harness got stuck. No one heard his yells over the music. And when a choreographer asked if he was ok, Justin said: “No. I am about to die. Get me down!”
He also broke his foot at London’s Wembley Arena when he was supporting Taylor Swift.
He said: “My foot rolled right to the edge of a ramp, and it felt like stepping on a railroad spike. In the middle of a song. In front of 12,000 people. And Taylor Swift.”
He made it to the end of his set, but said: “Once I got backstage, I howled like a dog. I won’t lie.”
No wonder he wants to go home sometimes!