The Parsons Green bomber has told jurors he lied to officials about being kidnapped by Islamic State because he wanted to study in Britain to become the new David Attenborough.
Iraqi asylum seeker Ahmed Hassan arrived in October 2015 and went on to tell immigration officials he had been forced to train "to kill" by IS, the court has heard.
Then on September 15 last year, the 18-year-old media student planted 400g of homemade explosives and shrapnel on a District Line tube timed to go off when it reached the west London stop, the Old Bailey has heard.
When he was picked up at the port of Dover the following morning he told police he had made the bomb, which only partially exploded on the packed rush hour service.
Giving evidence in his defence, Hassan told jurors he was never taken prisoner by IS.
Tim Moloney QC, defending, asked: "Were you ever mistreated by Isis?"
Hassan replied: "No. I have never had any contact with Daesh at all."
He told jurors he made up the story about being kidnapped by IS to get leave to remain in Britain.
Asked why, he said: "Because I came from a wealthy safe area in northern Iraq in Kurdistan and if I told the truth my only reason to leave the country was to further my studies ... I felt I had to make up something strong.
"In the jungle in Calais people used to talk about these things and make up stories. I never came across a refugee who said he would tell the truth when he arrived in the country.
"I wanted to go to university and my ultimate goal was to become a wildlife photographer like David Attenborough."
Hassan told how he was born in Baghdad in Iraq.
His mother died when he was young and his taxi driver father was killed in an explosion in 2006, he said.
"So far as I'm aware I was told that he died in an explosion while he was working as a taxi driver. He used to go to work and come back evenings and then he did not come back.
"It was very difficult. I did not understand what was going on. I was in a state of confusion because of fighting, because of bombing."
Hassan moved to northern Iraq with his uncle and older brother and from the age of 12 worked ferrying goods like vegetables across the border with Iran.
The defendant said he decided to leave Iraq because he wanted "a better life".
He said: "I wanted studying, I wanted to learn English and there was so much pressure on me to keep on with my job."
He smuggled himself to Britain by train and on a lorry at the age of 16, he said.
After he began a course at Brooklands College in Weybridge, Hassan would snap pencils in class when he felt "angry".
He spent three days in hospital because he "considered to commit suicide", he said.
But Hassan told jurors he enjoyed studying photography when he was at Brooklands College in Weybridge.
He said: "I enjoyed being behind the camera rather than in front of the camera."
The court was shown a series of pictures taken by Hassan, some of deer in Richmond Park, West London.
As a "secret" sideline, Hassan said he sold mobile phones online making £100 a week.
He said: "I kept it secret because I was not allowed to make money."
Hassan said it felt "good to be nominated" when he won student of the year in June 2017, adding he took the same title six years in a row in Iraq.
He has continued his studies while in prison so his "academic year is not wasted", he said.
Hassan, who was living with foster parents in Sunbury, Surrey, has denied attempted murder and using the chemical compound TATP to cause an explosion that was likely to endanger life.