Why some people have smartphones and smart cars that are smarter than them?

Definitely, but bear in mind a box of matches is smarter than some people.

The point isn't really new devices becoming smarter than people, it's people becoming dumber than literally anything.

well yes as most smart phones etc have way more capability in many areas than the human mind does.. anything you can think of it can find.

I believe the objective is convenience.

Not smarter just more capabilities.

Some people want to live their lives without having to think. So they seek devices to do that for them. Inventors comply.

Smartphones are making people stupid.

https://www.psychologytoday.com/us/blog/the-athletes-way/201706/are-smartphones-making-us-stupid

I've met people that were less intelligent than root vegetables.