Where do all the cheap smartphones come from that kill Apple's core business, the iPhone? Shenzen? Zuhai? Guangdong?

They even roll up the market of Asian cellphone makers like Samsung. Because they are good enough already. And cheaper.
Back oin the 70s, nobody ever believed a Japanese car maker could ever come close to the cars made by Germans. The little tin cans rolling down the ships in our harbours and then on our streets for first exploration, did not find many buyers. Bad quality, and too small and uncomfortable.
Today Toyota is probbaly the most quality-fixiated and one of the two or three biggest car makers in the world. VW. Ford. Toyota. And maybe Toyota before the other two.
I own Fenix torchlights. Made and developed in China. I swear on their quality. And their price is unbeatable, compared to torchlights of comparable quality and features from Western producers. Maglight? Surefire? Trunight? Zweibrüder? Ha! Cost twice as much, and cannot keep up. The biggest German special shop for torchlights has thrown these and many others out of their program - they do not sell anymore, people want Chinese Fenix instead! They have brought down the market, like they are about to do with cellphones as well. Notebooks. Chips.
Just examples. There are many more. China does its own aircraft. Tanks, helicopters. Just on the fly they did where the Europeans and NATO fail since over one and a half decade: within shortest time they developed and build a military transport plane that is as capable as the A400M, just carries more and bigger payloads. Different to the A400M, which is an over-ambitious crook that
many years behind schedule still cannot reliably operate and fly, the Y20 flies and functions, and has no orders grounding it. LOL.
What the Japanese and Koreans could do, the Chinese learnt to do as well. Since 25 or 30 years we deliver them the needed knowhow and technology, and tell ourselves that that were a joint venture!

They now have switched from importing key technology to producing it themselves - even and especially hightech. They copied us, they caught up with us, and now they are preparing to overtake us - at production prices that still are beating ours. Like tiny Japanese cars started to do 40 years ago. All the time while we are playing ball and feed them the knowhow they still need here and there. We made them strong, and we still do so.
We must have lost our marbles.