Trashfuture did an episode about Casper Mattresses, apparently a lot of these companies that advertise on podcasts get absolutely nothing out of the ads, like no ones buying a mattress based on a podcast ad plus everyone just skips the ads anyways (unlike TV and radio ads).

But its really cheap to get your ads on a ton of podcasts, which gives the perception that they are reaching a very large audience, which they can then parley into a big IPO. Its a big grift that, as a side affect, funds a bunch of podcasts.