In 2016, Morgan Mandriota and Lester Lee, two freelance writers looking to grow their personal brands, decided to start a podcast. They called it “The Advice Podcast” and put about as much energy into the show’s production as they did the name. (After all, no one was paying them for this. Yet.) Each week, the friends, neither of whom had professional experience dispensing advice, met in a free room at the local library and recorded themselves chatting with an iPhone 5.

“We assumed we’d be huge, have affiliate marketing deals and advertisements,” Ms. Mandriota said.

But six episodes in, when neither Casper mattresses nor MeUndies had come knocking, the friends quit. Today, Ms. Mandriota says the same D.I.Y. spirit that made having a podcast “alluring” is precisely what doomed the project. “You can talk about the trees outside as much as you want, but if you’re not going to serve listeners and do it in a way that’s engaging, your chances of going viral are low,” she said, calling her show “the most makeshift podcast, with mediocre advice.”

It’s no wonder that the phrase “everyone has a podcast” has become a Twitter punch line. Like the blogs of yore, podcasts — with their combination of sleek high tech and cozy, retro low — are today’s de rigueur medium, seemingly adopted by every entrepreneur, freelancer, self-proclaimed marketing guru and even corporation. (Who doesn’t want branded content by Home Depot and Goldman Sachs piped into their ears on the morning commute?) There are now upward of 700,000 podcasts, according to the podcast production and hosting service Blubrry, with between 2,000 and 3,000 new shows launching each month. In August William Morrow will publish a book by Kristen M einzer, a co-host of the popular “By the Book” podcast. Its title: “So You Want to Start a Podcast.”

There are dozens of books like Ms. Meinzer’s (with names like “Podcasting Hacks” and “Podcasting for Profit”). There is also a compendium, published by Podcast Junkies, titled “The Incredibly Exhaustive List of Podcasts about Podcasting.”