Because Claude Code is not a profitable business, it's a loss leader to get you to use the rest of their token inference business. If you were to pay for Claude Code by using the normal API, it would be at least 5x the cost, if not more.
I've seen dozens of "experts" all over the internet claim that they're "subsidizing costs" with the coding plans despite no evidence whatsoever. Despite the fact that various sources from OpenAI, Deepseek, model inference providers have suggested the contrary, that inference is very profitable with very high margins.
Just looking at my own usage at work, we’re spending around $50/day on OpenAI API credits (with Codex). With Claude Code I get higher usage limits for $200/month, or around $8/day. Probably the equivalent from OpenAI is around $100/day of API credits.
Maybe OpenAI has a 12x markup on API credits, or Anthropic is much better at running inference, but my best guess is that Anthropic is selling at a large loss.
How am I gonna give you exact price savings, when on $18 amount of work you can do it is variable, while $100 on API only goes a limited amount. You can exhaust $100 on API in one work day easily. On $18 plan the limit resets daily or 12hrs, so you can keep coming back. If API pricing is correct, which it looks like because all top models have similar costs, then it is to believe that monthly plans are subsidised.
And if inference is so profitable why is OpenAI losing 100B a year
source: pulled out of your a**