Comment by cdblades

Because the first couple major iterations looked like exponential improvements, and, because VC/private money is stupid, they assumed the trend must continue on the same curve.

And because there's something in the human mind that has a very strong reaction to being talked to, and because LLMs are specifically good at mimicking plausible human speech patterns, chatGPT really, really hooked a lot of people (including said VC/private money people).