I don't understand this at all. If you want to play and know a bunch of people who want to play too, one person just steps up to the plate and takes the DM roll. There is no special club or membership dues - just do it. Then step back and let someone else take a turn, then someone else.
You'll make mistakes, some will enjoy sitting behind the screen more than others, but just do it.
It can be intimidating, though, if you're in a group with people who have a lot of experience and skill, and you yourself have never done it.
In my group, there are two of us who've been gaming a long time and have lots of experience sitting in the big chair* (30 years for me, 15 for the other guy). There are two more who have less experience, but they're gung-ho extrovert types who are always up for a leap into the unknown. So all of us have no hesitation at all about DMing, we're comfortable and confident in the role.
And then there's the fifth guy. He's been a casual player most of his life; if there wasn't a DM available, he didn't game, and that was fine with him, he had plenty of other stuff going on. Since joining our group, he's slowly gotten more involved, and developed his level of system mastery from "near-zero" to "fairly competent." But it's taking a while for him to shed the idea that he's a casual player who can't handle complicated rules. It was a big milestone for him to even try a new character archetype; he's spent his entire gaming career playing stealthy skirmishers (rogues and monks), and only just now decided to give "front-line tank" a whirl.
As I say, I think he will eventually take the plunge, and I think he'll be quite good at it when he does. But I can totally understand why he's hesitant. He's contrasting himself with everyone else at the table. In his place, I'd be doing the same.
[size=-2]*Literally. Our game room has two padded, ultra-comfortable, leather-covered chairs and several cheap plastic ones. One of the comfy chairs belongs to the guy who owns the house, and the other is reserved for the DM. I just came off a two-year DMing stint, and while I'm very happy to be able to relax and play a character for a change, I sure do miss that chair.[/size]