Good for you, but many other people appreciate the curated platforms that Google and Apple have built and like it that way instead. They're not 'insane' for liking it a different way to you - there's benefits of both approaches.
And it’s not just dumb people downloading from shady sources. Look for a printer driver online and you’re just as likely to find a fake malware site as the real site.
The need for trusted sources for downloading apps with limited permissions can easily be seen if you look at some people’s PCs - or Android devices.
True on Android, too. And both platforms have OS vendor app stores.
After spending an insane amount of money creating and supporting these things, it seems completely justifiable that Google would then ask for a cut of the profits for applications that are built on top of the tools and infrastructure that Google provides for free.