Rich artists sell a lot more CD's of one album than Dan has with all of those...
yes, sadly
Why the world needs 7 million copies of Jennifer Lopez / Jay Z-records I can´t grasp.
Several years ago in an interview was debated about how much was sold of the main projects, and if I remember correctly, EOS alone sold more than everything else, including NG.
Many things of this list are very rare releases, that you can get once in a while on ebay, it´s not on no. 27 at amazon or such. Other projects were (thank you!) released in the net, like on Dan´s megapage. Also note that one list begins with "Bands that rehearsed at least once / bands documented on cassette", so that´s pure one/off-projects for music´s sake, not the billboard-charts.
Artistically it is an incredible list *worship*, but financially I think most comes from Edge Of Sanity and the enormous amount of studiowork.
EDIT: I read in a Children Of Bodom-interview, that Peter T has it in his contracts to get a percentage of each CD he worked on. So it was for COB´s "Follow The Reaper", and a good chunk of money went into the direction of Sweden, since it sold pretty good (It was also the reason why COB didn´t want to repeat this again, even though Tägtgren´s work was of course excellent). Peter T recorded / produced a lot of stuff, so if that part was in each contract, he got good income from it.