Ask HN: Expenses of building AI-powered SaaS?

I'm curious about AI-powered startups launching every day.

These AI APIs are paid e.g. OpenAI GPT-3.

How does it make it worth building for people? All these startups make money or what?

Having thousands of free users would cost probably hundreds of dollars. How does it make sense?

I was thinking about adding AI to my note-taking app, but I think the cost would be too much for text-autocomplete with AI.

Am I wrong or what's your opinion on that?