You're comparing apples to oranges; I don't equate "sales" with "genius"
Gee, I guess I made the mistake of confusing astounding sales, influence, and critical acclaim with genius. How do you explain the fact that such large numbers of their contemporaries, along with so many musicians that have come along since their demise, name them as an influence? Why would Frank Sinatra refer to "Something" as one of the greatest love songs of all time? I guess you would say luck?
I think "genius" is too strong of a word to apply to any musician or musical group of the past 50 years.