Also, remember that, unlike a lot of bands that have a big hit then piss all the bucks away, DT has been set up where all the bands income goes into a central account from which a salary is paid to each member. With 10 studio albums (including one gold record), several live releases (including several platinum-selling DVDs), and tour income over the years, they've probably all got a nice, steady income. And, I'll bet a lot of that got invested, yielding investment income on top of that.
And, they almost certainly get a much larger cut of the album sales, since they switched to RoadRunner.
So, I'll bet all the guys are doing pretty well, with MP taking in even more from his side projects, etc.