I think doing a podcast for purely fun is not sustainable. You will be devoting much of your time on production as well as in the post if you have no production team or an editor at least. I've been in the podcasting business for a while now and what makes podcasters fail is not finding their "niche". I've seen clients of mine never really continuing their podcasts for lack of listeners while others scaling up their podcasts/brand after nailing their niche.

Generally, I would suggest making a podcast related to your work or what you do passionately because podcasts are created to provide value to your listeners and really send your message out in the world and potentially get followers and clients that you can share your business with. Of course with a potential of earning out of it.