This is because we are looking at the trajectory not just their current capabilities. LLMs went from barely being unable to focus on a task to purposefully escaping sandboxes within like 2, maybe 3 years?
Human history is full of examples of this stuff plateauing and hitting hard scaling walls. Not only technology wise but economics and useful applications.
So much of this tension with AI is because everyone's concept of AI comes from movies and books, and nerds drinking Kool aid (see also: web 2.0).