They have good margins on inference at API costs, i.e. $5/$25 per mtok input/output. They are almost certainly making losses on subscriptions, at least if people max out rate limits.

In the past 30 days I have burned $78.19 in API token costs with my $20/month Claude Pro subscription. In January I burnt over $300 in API token costs.

Because the power users of the max plan are subsidized at the upper end of usage by people who don’t approach the per account limit. In other words, the power users are getting more than they pay for, because most people don’t reach that threshold. If you let the power users have dozens of accounts, it has a multiple effect on the proportion of accounts breaching the profitability line.

They are likely aiming to maximize reach/mindshare. Get as many people hooked as possible. More important than minor upside from a few multi-Max users.

EDIT: also, the casual or gym-style members that pay every month but barely use the service are of course very valuable wrt margins