FB/Meta and Google likely had similar ambitions and they haven't succeeded in building one despite being in a far better position to do so. Google Maps is probably the closest thing we can get to a mega-app in the Western world, for now.
”Buying Twitter is an accelerant to creating X, the everything app”
Yes, multiple things can be combined, but if it works, probably just coincidence.
I can also imagine how people might find it convenient to have essentially browser, messaging and payment combined into a single thing (essentially WeChat) they can use instead of a variety of separate apps/accounts.
But I'm also sceptical anyone can make that happen in democratic capitalist countries without insane amounts of investment.
But outside web-browsers, I'm not sure it is anything anyone wants - like you imply, in China it's probably handy, because it is a reliable route into all the services that are blessed by the CCP, which means you avoid running into firewalls & thought police.
1. Everyone else has it
2. You can pay with it anywhere (pay in shops, pay people, pay online)
The Apple and Android app stores are everything apps.
Twitter, Facebook and WeChat are mainly valuable because others have it.
You may be immune to the network effect, but then again, you’re commenting on Hacker News. :-)
Grab and Careem are both decent attempts at it
If Elon Musk is still serious about building a mega-app then he needs to rapidly acquire/launch a lot more companies in consumer spending sectors e.g. entertainment, hotels, delivery, restaurant reviews, etc. But linking to those services within the mega-app would run into trouble with anticompetitive lawsuits pretty much everywhere.
There is a big hill for Elon to climb yet he's only focused on kicking rocks barefoot at the bottom of that hill.