Wires don't just work when they get tangled or broken.
Wireless doesn't just work when it runs out of batteries, gets glitches/interference, or is hassle to pair.
Apple was able to tip the 'just works' balance through good engineering.
That's Apple's point of failure. The rest of the industry (mostly) has worked out how to make a headphone jack water-resistant.
That's Apple's point of failure. The rest of the industry (mostly) has worked out how to make a headphone jack water-resistant, years before Apple made any phone water-resistant at that.
Yes, by removing the headphone jack on high-end phones, just like Apple did.
Let's not pretend this is an Apple vs. The Rest Of The Industry sort of thing. The whole sector is going that way; Apple just took the lead.
See also: Floppy drives.
No, this is clearly incorrect. As I said in my original comment, there were water-resistant phones with headphones jacks years before Apple released one without a headphone jack, and there are ones being released now as well. While Samsung removed a headphone jack for a generation of their flagship phones, the generations before and after were both water-resistant as well. Samsung's newest releases (S10 Lite and Note10 Lite) both have headphone jacks and are water-resistant.
From years ago: https://techcrunch.com/2014/02/27/apple-if-samsung-and-sony-...
To do away with the point of failure that you so aptly illustrated by getting salt water in your phone?
I wouldn't have bothered with the AirPods if my headphone jack had continued to function.
That's you, though. There are clearly millions and millions of people who don't want wires.