As someone trained in the sciences and engineering, "drawing a straight line" is almost always the wrong way to extrapolate.
I can believe my profession will be impacted strongly. That doesn't worry me on a global scale. The only really worrying thing I've seen are autonomous bots hacking sites.
What worries me more are humans. The type who get so deluded into cults (QAnon, etc). That was a problem before LLMs. And yeah, LLMs likely will exacerbate the problem. But at its core, the problem is the humans.
When LLMs start killing people at the scale of the automobile, I'll become more concerned.
As an aside, HN is the place I see people most regularly concerned about LLMs, and I suspect it's because it has messed up the Internet for them (and likely the average HN user spends more time online operating in spheres that overlap the LLMs skillset than ordinary folks). It's very consistent with exposure bias.
For me, the good parts of the Internet died before LLMs even came on the scene. LLMs are merely making something crappy crappier, and are amplifying the need to find meaning in life elsewhere. In a sense, they've made it easier to see how bad the Internet was before they came along.