It's easier to just have 10% of listeners pay $10/year and go ad-free. Advertising is a pollutant and no longer necessary in the new at-scale world.
When you have a small podcast, you can just do it for the love of it and not worry about money. If it gets big, you can get a small percentage of your listeners to give you money. The number of contributors should continue to rise for many years as more people discover how great podcasts can be.