Looks like the best bet is to stay real small so you don't need a personal manager or a business manager or a lawyer or a publicist of a manicurist or a bass player or drummer or singer or a record label. Looks like you would make more money standing on the corner with your guitar case open for tips. Like Mr. Entertainment said (Sammy Davis Jr.) "Show-Biz darling that's two words. Everyone loves the show and everyone hates the biz!" Peace on you.

I'm surprised the drummer gets an even share. Seriously though... 

Steve Albini's article on the record industry is jaw dropping.

http://www.negativland.com/albini.html

Paul, while your math is correct the trouble is getting the record company to admit that you made a million or sold a million. There is a endless stream of stories about discs being printed in the night and sent out the back door and never accounted for to the artist. In other words they get 0% of those record sales. I believe it was Mitch Mitchell of the Jimi Hendrix band who said that if he knew then what he knows now he would go into the music business with a lawyer in hand and a machine gun in the other.

These numbers are somewhat close but reality is worse. This assumes everyone in the band shares the publishing equally (a rare instance), or that the band even writes its own material. Big name producers often get 4-6% of a record.

And as WTF said, the devil is in the accounting. Tracking and getting paid for sales is the hardest part and the big labels will do everything in their power to make it as difficult as possible. Counterfeiting was and still is rampant; lots of CDs sold are outright counterfeits from overseas sold with or without the complicity of the record label.

The age of digital downloads has made it even tougher to make any money. Itunes keeps a large piece of that 99 cents per song; the artist sees very little and other digital distributors are even worse.

It used to be possible to make a modest middle class living through touring, merch and music sales but that is rapidly eroding to the point where a lot of players are simply throwing in the towel.
 
And don't even get me started about studios and the recording business.