Axl owns the rights to use the term "Guns N' Roses" on whatever he wants - which is worth an absolute fortune. He took that right from the other founding members back in the mid-90s. He owns it exclusively.
Appetite for Destruction has sold over 18 million copies in the US and 30 million worldwide.
Use Your Illusions (1 and 2) were released at the same time. And were ranked #2 and #1 on the sales charts respectively when released. Both albums have sold over 7 million copies each.
And Axl has regularly toured as Guns N Roses- he kept the profits of a show and paid all of the non-founding members as hired help. So he was pocketing millions off of each of the tours that did not feature the original lineup. Even though they were not selling out major stadiums, the various tours and Vegas stint made Axl a lot of money.
In this latest tour and reunion with Slash, the three founding members are splitting profits and the remaining players on stage are hired help. From what I have read so far, they are making millions off of each show and there are 25 in the US alone. They are going to embark on the South American tour later this fall and I am sure a visit to Europe will be announced.
Thus far, the shows in the US have all received AMAZING reviews. I was at the show in Foxboro and was blown away. Axl is going to make a BOATLOAD of additional money in the next few years.