I had the same exact thought. It might be that this graph represents month-by-month net income, rather than something like Net MRR. Perhaps the spike represents a large number of sign-ups for annual plans (it seems like his standard plan is $24/year) in a short period, which means he should see the same spike next year upon renewal (minus his churned customers, of course).

It might be that if he "pro-rated" the monthly payments for his annual accounts as $2/month payments for the future 12 months, he is net positive right now. It's hard for me to tell by eye from the graph, but it's probably close.

Well if those were annual payments it might be profitable spread over the whole year (my visual integration skills can't quite tell) and there should be another massive spike just about to start as all those people renew their subscriptions.