This is how Firebase, Supabase and friends work.
Getting 100 people to sign up for a free service is still work, but significantly less.
If not, then you are in the ad business.
I suspect there's a special dynamic for developers. I'm usually more willing to try out new things on personal projects, but I also don't like paying for things on personal projects. At work I don't care how much things cost, but I'll definitely advocate for tools that worked well on personal projects.
Ideally you want your tools to be so easy to use, clients just switch onto a paid plan when they want to get serious.