Well, this statement is only true when it comes to music games. According to some NPD number, Guitar Hero Aerosmith has sold more the Rock Band Beatles.

Guitar Hero Aerosmith — 2,741,000
The Beatles: Rock Band — 1,296,000
Guitar Hero Metallica — 1,001,000
Guitar Hero: Van Halen — 94,000

Could this have to do with the generation playing video games now growing up more with Aerosmith then the Beatles? Or is Aerosmith more suited for a musical game then the Beatles? Questions that will haunt me for the next five minutes.