Unless you're famous, wildly charismatic, or have some very specialized knowledge I'm not sure how you break into the podcasting game.

There are only two real options:

1. Be part of an existing popular podcast. If you get to be a guest appearance and you're charismatic enough, you can get invited back more often until you're a regular. Get good enough to get your own following and then you can eventually break off and do your own thing with sponsorships from the get-go.

2. Be famous for something else first. If you're a celebrity, author, streamer, YouTube personality, etc., you can start a podcast from nothing and have your sponsors and listeners already lined up.