The G4S chief said that his firm still planned to collect its £57 million management fee despite the ongoing Olympic security debacle.
Nick Buckles - who insisted he was the right man to make sure the company delivered as many guards for the Games as possible - told the Home Affairs Committee:
Keith Vaz, chair of the Home Affairs Committee, said: "I find that astonishing."
Mr Buckles apologised and said he was deeply disappointed after the firm - which is running the £284 million contract for the London 2012 Games - failed to meet its targets.
G4S are now aiming to provide a minimum of 7,000 security guards, a long way short of the initial 15,000 promised.
Mr Buckles - who is under pressure to quit his £830,000-a-year job over the fiasco - told MPs that it was a "complete and utter shock" when he found out on July 3 that there would be problems delivering the contract.
The G4S chief added that he told organiser Locog on that day that his firm had experienced a shortfall over the weekend, in part due to its scheduling system not working properly.
It was not until an Olympics Security Board meeting, chaired by Charles Farr on July 11, that the firm said it was not going to meet its contract obligations.
Asked by Labour MP David Winnick if it was a "humiliating shambles for the company", Mr Buckles said: "I could not disagree with you."
And asked if he agreed the reputation of G4S was in tatters, Mr Buckles said: "At the moment, I would have to agree with you." He insisted the firm has had a good reputation "over the years", but added: "At the moment, it's not a good position to be in."
Mr Buckles said G4S took on the Olympics contract to boost its reputation.
But he insisted the £50 million loss the firm now faces was not insignificant, saying it was a "huge amount", representing 10% of its annual £500 million profit. "It was a hugely important contract," he said.
Asked about staff not turning up, he said, "our normal show rate is about 90%" but he said it was not an issue of people being told to turn up and not arriving.
G4S will pay all military and police costs caused by its failure as well as any accommodation costs incurred, Mr Buckles said. Asked if it would also pay bonuses to the military and police, he said:
Pressed further, he said bonuses would be considered, "particularly for the military personnel who have had to come off leave to cover the Olympics".
Mr Buckles later admitted he could not even guarantee how many security guards would turn up on the first day of the Olympics but he added that it was his "expectation" that 7,000 G4S staff would turn up.
He added that 500 extra troops were also being held in reserve, in case they were needed.