Vunipola turned down corporate cash to revive England career
The Saracens No 8 was one of several senior players dropped by Eddie Jones last year, with the England coach expressing doubts over their ability to get through another World Cup cycle that would take them to next year's global showpiece in France.
As a result, Vunipola, who turned 30 on Thursday, missed an entire autumn campaign and Six Nations.
But his response was to try to prove Jones wrong by starring for London side Saracens, with Vunipola turning down the chance to earn what could have been close to a six-figure sum by hosting supporters at England home games.
And such was his club form, Vunipola was recalled for England's successful tour of Australia and the powerful back-row is now in line to win his 65th Red Rose cap against Argentina at Twickenham on Sunday.
"Sometimes it's not about money, it's more about how you want to feel, how you want to present yourself," he said Thursday.
"I didn't want to be one of those guys who was just happy to be dropped. That's how I assume it to be - people just turning up at Twickenham, happy to take the cash. I wasn't happy just to take the cash. I wanted to play."
He added: "There are marquees everywhere (at Twickenham) and they want to throw cash at you to do appearances.
"I didn't want to do it because you say one thing wrong, someone sends it to the press...I want to be playing, not sitting with 100 drunk people asking me questions about Eddie."
Vunipola was well aware of Jones' intentions when he commented about his "hunger" for Test rugby, even as the loose forward struggled to come to terms with Saracens' relegation to the second-tier Championship for the 2020/21 season.
"I kind of just laughed it off and thought 'okay, he knows what he's doing and it's a challenge he has laid out for us, for me'. He was right," Vunipola said.
"When he is questioning your hunger, motivation and determination, if you get annoyed by that then a lot of what he's saying is true.
"My hunger didn't wane as such, but I probably became a bit disillusioned with playing in the Championship. It was tough to play at that level then slot straight back in with England."