I think there are probably a few reasons that many people reject these ideas. I’ll try to rattle some off:
Hollywood Effect - “You’re joking right? I remember that movie from last summer.”
Linear Extrapolation - Like Kurzweil talks about. “Yeah, maybe in a million years.”
Failed Promises - For how many decades were we supposed to already have Strong AI?
Religious Beliefs - The future is in the hands of this deity, we can’t do anything about it, so don’t try. And don’t make him angry.
I’m Uncomfortable - These explorations are often not very reassuring.
I’m Bored - “I don’t like reading, all that much. When is the next football game?”
Yuck Factor - “You want to do WHAT with your body?!”