Tiesto has made an estimated $65 Million dollars in the past 10 years. We are spoiled to have him here 10 times a year (Thanks LIV), but he is usually to expensive for most other cities, who's clubs aren't able to charge their patrons $200 cover to see him.
DJ's are making some serious money now. This makes the "DJ's aren't Rockstars" T-shirt obsolete. Now DJ's are demanding more money than most actual performers and have become celebrities in their own right. Some have crossed over into Hollywood land and have began dating high profile celebrities (Afrojack was pouncing on Paris for a little while and actually even had the pleasure of braking up with her!). 
What we found surprising was that David Guetta was so low on the list. We thought that he would rank much higher considering his recent success in crossing over to pop music.