There seems to be a big 'diminishing returns' factor for regular readers, presumably meant to deter 'read-for-read' circles. But that would also have the effect of boosting new writers, as all their readers are 'new' as well, so they get the full payout from their visits - to begin with.

This has the added advantage for Medium of getting people hooked, but unrealistically front-loading the typical earnings. FoM Reader A who has just discovered you might be worth 10 cents a read, but a few months later, if they keep reading, that will be down to less than a cent.