On Episode 258 of Marco Arment and “Underscore” David Smith’s podcast Under the Radar, and then on Episode 516 of Marco & co’s Accidental Tech Podcast, Marco describes the fact that his data suggests that about 12% of his users don’t have logged-in iCloud accounts with iCloud Drive enabled, which was a significant obstacle to moving his sync system for Overcast to use Apple’s CloudKit, which requires both.

This was a surprise to Marco, who had expected that the figure would be closer to 1%, and led Casey Liss to worry aloud about producing an app that depended on CloudKit.

Marco, entirely correctly, suggested that his user base may be non-representative, and pointed out that

1. Many people listen to podcasts at work and when commuting, so may be more that usually likely to use work-issued phones; such devices are often locked out of use of iCloud in general, and iCloud Drive, most specifically.
2. His users are almost certainly biased towards geeks.

It may not be immediately obvious, but there is also a strong “statistical” explanation for why Marco is almost certainly right, and Casey’s fears are likely to be somewhere between exaggerated and unfounded.

TL;DR: Self-Selection Bias and Customer Stickiness

Overcast is unusual (possibly unique) in offering a non-CloudKit-based sync system. Users who need non-CloudKit-based podcast syncing have a limited choice of options, possibly Hobson’s Choice. So it is extremely likely that Overcast has a disproportionately high number of users who can’t/don’t use iCloud Drive. Interestingly these people might also be exceptionally loyal, because they (perhaps) have nowhere else to go.

The Long Version

Let’s do some Fermi Estimation.

• Let’s suppose Apple has 1 billion iOS users.
• Let’s suppose 10% of them use a podcast player. That’s 100 million people.
• Let’s suppose (consistent with Marco’s assumption) that 1% of those don’t have a logged-in iCloud account with iCloud Drive (forthwith to be refered to as “iCloudless”). That’s 1 million people.
• Let’s suppose Overcast has 1% market share (1 million active users).

Understandably, Marco doesn’t release user stats per se, but did say:

“So, to give you some idea of what I mean by ’hardly anybody uses it’, I’m looking at a few hundred people who use the website, and that is not a large portion of the user base. And this is ... per day. ... It’s under 1,000 people. ... snd that’s ... well under 1% ... [I]t’s a very small portion of the user base.”

— Marco Arment, Accidential Tech Podcast #516, One of My Fits of Outrage, 3rd January 2023, from 31:16 (listen here).

That sounds consist with a million users, and certainly says the number significantly exceeds 100,000. Further, BuzzSprout’s Global Player stats for December 2022 put Overcast’s Market Share at 1%,¹ with that number pegged at 1,134,026² (users, presumably).

Based on these estimates, there are the same number of iCloudless podcast listeners—one million—as there are Overcast users, and their only choices are * to use Overcast, * to find another podcast player that offers non-iCloud-Drive-based sync (if there is one), or, * to forego sync. This is the self-selection bias. Just as restaurants with good vegan food probably have a disportionately high number of vegan customers (and much higher than ones that don't cater for vegans), and buildings with proper disabled access probably have disportionately high numbers of disabled customers (and much higher than those that don't offer disabled access), a podcast player that supports iCloudless sync will almost inevitably have a disproportionately high number of iCloudless users. In principle, if the estimates are reasonable, Marco could see up to 100% of his users in this iCloudless category without running out of iCloudless users (though this would plainly be ridiculous).

If these estimates are the right order of magnitude, 12% seems like a very plausible figure for what Marco would see in his stats. It means only 12% of people who might benefit from the sync service are using Overcast, but that’s an order of magnitude more than its estimated market share, which is pretty good. It also means that 88% of podcast listeners who might benefit from iCloudless sync are not currently using Overcast.

As I said, I don’t know whether any other podcast players do have an non-iCloud sync service, but either way, it also suggests that now that Marco has put his plan to discontinue it on ice, it might not be a terrible idea for him to lean into it. Maybe his marketing should specifically try to target users who want to sync podcasts across devices (and the web!) but are “iCloudless". After all, it’s very plausible that there are a million of them out there; and it would be really hard for Marco’s competitors to respond. As noted above, these also might be exceptionally loyal/sticky customers, because there may be nowhere else for them to go. It’s one of Marco's stronger competitive moats.