It's an oxymoron. Everyone above says so, in different ways. So the only way has to be - transcend "folk" and enter the realms of "popular"; be noticed by big-buck publishers and promoters, and sell tens and hundreds of thousands copies of each album, as opposed to hundreds or (at best thousands); be invited to write music for big-studio films.
Others who started in the world of folk did that. Mark Knopfler, for example.
And did he sell his soul to the devil? Is he less of a folkie now? Just listen to his "Sailing to Philadelphia" album, and you'll get the answer.