Can you read 20 articles while driving a car or walking to the store or cleaning your house? I find they're a great way to double-up with activities where I'd otherwise be bored out of my mind, and I can take the opportunity to learn about something, or at the very least not be bored.

TV might be more entertaining, but I've never heard anyone argue "Why would you sit down and watch the new Game of Thrones episode, you should listen to a podcast instead!" Being an audio-only medium makes them a lot more amenable to consuming while you do something else. They're only competing with music and audiobooks in that respect.

It's not like I get home from work and think "You know what I want to do this evening? Sit in a chair and listen to podcasts for an hour."