I guess Bitcoin could be used for large transactions, but i don't see the point in it, apart from bitcoin having the biggest net value for the moment.
In the end its only a digital number that is transferred, that number being bigger or smaller doesn't make to much of a difference. I mean one Japanese Yen is worth less than 1 us cent, but that doesn't stop them from buying cars and stuff with yen. What would make a difference though are transaction fees.
Paypal can actually be compared to BTC. Most people don't yet care that much about centralized or decentralized systems. And as far as money transfer goes it isn't that important, more important to the average user would be price stability, transaction speed and fees.
If we talk about investment etc. Bitcoin and Paypal are vastly different.
RE: Bitcoin use case in my view and why he will stay the KING