“Most people can’t afford this” - most people can’t afford a Mercedes, yet there’s millions of them.

I don’t think that’s that bad, especially because the pressure drops everywhere equally. Most planes would be able to work just fine, they’d just have to fly a bit lower, if even that. Divers would get squashed though.

If we’re only talking about oxygen as in O₂, you’d probably be mostly fine. Even if we’re talking anything that contains an oxygen atom getting destroyed, something like Silicon would be so much worse - most of the Earth’s crust would just be gone. Hydrogen would probably also be fun, because it’d turn water and any organic compound into oxidizers.