Jaime Alguersuari and Sebastien Buemi were both axed from Toro Rosso in 2011
"All of us who have gone through Red Bull have been machines," Alguersuari told AS.
"That is the school we had. Either you win or you die. It was all a matter of survival or death.
"We have all felt that maximum pressure from Dr Marko. Carlos, Vettel, Buemi, me... there were calls in which he told us 'If you don't win the next race, you won't race with us anymore'.
"If I hadn't won the British championship in 2008 I wouldn't have continued. We were always on a knife edge."