I think the point that is missed is all of these solved real problems that needed solving. I feel over the last decade we have exhausted the obvious benefits of the Internet revolution and more often than not we were seeing clever technology being developed, that wouldn't solve any problems. Then long and painful search for applications of that technology would ensue. Cases in point: crypto, llms.
I'm not sure I agree on your definition of legitimate...
If we want to say that any value generating - including crime - is inbounds, then LLMs are FANTASTIC scam machines. There are incredible uses for LLMs in a lot of stealing money spaces.