If you're going by the standard definition of "pro", which is anyone who's ever been paid by a client for their work, I'm willing to guess a lot of these guys already were pro. If they weren't, they are now.
But why would you ever want to exclude someone based on their professional status and not the quality of their work? If I was an editor and I saw great photos coming out of someone I've never heard of, I'd hire them in a second before I picked up a "pro" whose work I didn't like. Besides, I'm sure they saved a ton of money this way. Hey, they're in business to make as much as possible, just like any other business. There's a reason they're worth so much.
