For years, Harry Stebbings, the hit British podcaster and venture capitalist, fired off emails to Marc Benioff—no fewer than 53 of them—hoping to cajole the billionaire into appearing on his show, "20VC."

"I emailed him every week with no response, and then he finally did reply," said Stebbings, 28. Finally, Benioff appeared on an episode of "20VC" last September, discussing San Francisco, Salesforce and raising wealthy children. "And now we're on WhatsApp together. It's great."

Stebbings' tenacity has turned "20VC," which debuted in 2015, into a new Silicon Valley must-listen, partly because he lands great guests. That includes Sam Altman, Reid Hoffman, Vinod Khosla, Flexport's Ryan Petersen and seemingly every other major startup founder. Stebbings' conversations aren't journalistic—they're much chummier, more fanboyish—but he has certainly filled a Rolodex that would be the envy of most journalists.