On Business: Success
Of course, that success is not without its detractors. Some of his works have garnered him a reputation for being homophobic and misogynistic, and his public comments about Occupy Wall Street and Islam have been open to quite a bit of criticism. More recently, a number of people have suggested that he might be battling some form of cancer, judging by his seemingly rapdily deteriorating appearance. (For the record, I have no knowledge whatsoever of the actual condition of his health, but he sure doesn't look good for someone still in his 50s.)
So is Miller successful?
But Miller's success, however you might care to define it and despite any conditional statements you add to it, is only valid for Miller. Not for his contempories like John Byrne or Walt Simonson, not for anyone trying to follow in his footsteps, not for anyone in the comic business generally, not for you, not for me. Miller has his own yardstick to measure himself against.
Success in comics is however you personally define it. Maybe that's earning enough money from comics to eke out a living. Maybe that's having a certain number of people read your work. Maybe that's getting a shout-out from your favorite podcaster.
That's not to say you can't have lofty goals, of course, but don't use someone else's criteria for success as your own. You don't know what goals they were actually working towards in the first place, and the conditions under which they succeeded are almost guaranteed to be different than whatever conditions are present for you in the second. You're much better off, and more likely to succeed, if you establish your own goals and your own method of working towards them.
I've been told that Jack Kirby was not infrequently shown artwork drawn by aspiring creators that did their best to match his style. Regardless of how closely they did that, or how well-executed the piece actually was, he told them not to copy him. Rather than be a pretty good imitation of Kirby, they'd be more likely to find success by being the best version of themselves they could be. Great advice then, and great advice now.