You don't need a large audience for podcasting, you need an audience of whatever size to break bread. If you have 2500 listeners and 200 give you a dollar then you made 200 dollars that show.
2500 is enough to attract advertising to your group of 2500 Hit them in the head for Free products and a hundred each to advertise and you get two sponsors at a hundred each. 200
Now thats 400 a show off 2500 audience
We haven't even factored in YouTube views and other potential gigs like hosting events.
Its not about how many people listen its about how many people are willing to break bread and the connection you make with your audience