Todd Wagner is warning nonprofits to go digital in their fundraising efforts or die from natural causes in the not-too-distant future. “Technology is a freight train coming down a mountain,” says the billionaire philanthropist. “It is not going to stop. It’s only going to go faster. And either nonprofits embrace it or they get run over by it.” So the 56-year-old founder and CEO of Dallas-based Charity Network is offering them a death-defying route. Wagner is using some of the billions he’s made from being Mark Cuban’s partner in and other media and entertainment ventures to create a one-stop shop for philanthropic fundraising.