He may be one of the biggest rock stars on the planet, but Grohl readily admits he and the Foo Fighters, who play Wrigley on Sunday and Monday, are amazed at what their life has become. The Grammys they’ve racked up? The collaborations with music icons such as Paul McCartney and Iggy Pop? Grohl and his Foo Fighters bandmates— including drummer Taylor Hawkins, guitarists Pat Smear and Chris Shiflett, bassist Nate Mendel, and keyboardist Rami Jaffee — often find themselves wondering how they succeeded so gloriously where so many others failed. “A lot of the times we just feel undeserving of a lot of it,” Grohl says. The singer-guitarist recounts one particular moment from last summer’s European tour when the band showed up at an airport only to discover they’d been allotted their own private jet. “And this plane was gigantic!” Grohl recalls with a laugh. “It was crazy! Taylor (Hawkins) and I sat in the front of the plane and said to each other, ‘We’re not good enough to have this plane! We need to get to the practice room and get tight!’ ”