I think of the Beatles like of any pioneer, they are basic but entertaining.

For example, I love ham and cheese, but that's not going to be the only sandwich I eat until the end of my life. Sometimes I want some mayo, or bacon, or maybe some turkey. Now, ham and cheese has been around for a long time, but that doesn't make it better than my turkey ham and cheese sandwich. It just means it has had more time to be good.

It's entirely unfair to compare the Beatles to any artist past the 70's, as they have had more time to sell units. Think of your favorite artist in the last year (mine would be Walk the Moon at the moment). Are they great? Fuck yeah they are. Will they be great in 50 years? Maybe, we won't know until it happens.

What if I compared the Beatles to Patty and Mildred Hill? They look like a Teen garage band compared to them. The Hills wrote "Happy Birthday" if you don't know, it still earns billions of dollars even today. If you see someone singing happy birthday on a mildly public event? It's being paid for. That song has also been in use since 1893...so they have a bit of an advantage, no?

I don't mean to rain on the parade, but it kind of irritates me when people make modern day comparisons to The Beatles. They are in wildly different situations. Back in the day, The Beatles were just as hated as Bieber (well....maybe not that much) because they were teen "pop" stars. People hated them because they had what people wanted to have. Everyone has fucking blinders when they look back, because it's been so long.

It's like Jimi Hendrix. Was he tremendously talented? Yes. Was he kind of an asshole? Yeah, actually. He died in a pool of his own vomit. He defected from the army corps. But what do people remember? His playing of the star spangled banner, and "purple haze". Not even his best material.

Also, another thing that bugs me, why did OP pick these particular artists? They aren't all even the best selling artists of their era. Why not pick Elvis, Michael Jackson, Madonna and Elton John (the other top 4 best earners in history)? It's a fun useless fact, but you could use this same fact for Elvis if you take out any one of those artists.

TL;DR The Beatles have indeed sold more. They've also have a 40 year handicap on Tupac and Nirvana, as well as a 50 year handicap on Kanye. Why OP chose them is beyond me.