Providing ready-made UI components and templates has never been a million-dollar business, nor should it be.
Arguably many websites and apps desperately need a good component library because it's very clear the UI sucks without one. Lots of people spending a few thousand dollars on their UX is not unreasonable at all, so the best-in-class library (whether that's Tailwind is a separate point) should be able to make a lot of money.
You could easily level the same argument at any library: "This thing is simple so it shouldn't be worth millions." That's just the wrong way to look at how selling works. If you make something that solves a lot of people's pain point (Tailwind) you're going to make a lot of money until someone else sells something that makes it even easier (AI). That is a tale as old as time, and the fundamental basis of how startups disrupt incumbents in an industry.
The pain point tailwind supposedly solves is that people who are supposed to be front end web developers don’t understand CSS.
I don't agree with the other commenter. The point you make is a fair one.
However, I think the real information in your comment is that there are people making websites and web apps who aren't frontend developers. They're likely fullstack who are much more backend focused, and who do the frontend more out of necessesity than enjoyment. Tailwind enables those people who aren't experts in frontend to make things for the web without the necessary expertise to write CSS themselves.
That's why it's valuable - the point of Tailwind is that it solve the pain point (not knowing CSS) with money instead of time. But now people can solve it with AI instead.
This is a poor analogy, but maybe we should consider CSS as a lower level language than Tailwind, similar to JVM bytecode to Java. There are plenty of people who will tell you that a real Java developer understands the bytecode, but that doesn't stop people writing code in Java without knowing the lower level.
That’s like saying a carpenter doesn’t understand woodworking because they sometimes buy pre milled lumber. Or that landscaper a doesn’t understand mowing because they don’t trim each blade of grass individually.