It is limited because there can be maximum of 21 million of Bitcoins, and no more. This produces scarcity.
It is verifiable because it's based on the blockchain technology. Anyone can verify that you actually own the money you claim to own. In the fiat system, you have to rely on the banks for that, and banks can be painful at times.
It's anonymous because you don't have to attach your personal information with the wallets. Creating a wallet is as simple as generating a random number. You need no permission from any higher authority (banks).
Because of the above reasons, Bitcoin is unblockable. No government can block it, directly. They have to adopt indirect methods like heavy penalty on being caught, blocking internet services, banning exchanges (which aren't fundamental to Bitcoin). And since it is anonymous, no person can be banned from using it.
So yeah, the value of Bitcoin is that, it is a medium of exchange for value, but which awesome features. Saying it is valueless, because it doesn't produce anything tangible is just being naive.
There are many ways to skin a cat, especially in finance.
Soros made most of his money betting on political and social trends. People just don't talk about Soros as much because he's too far from the top of the Forbes list. Poor guy is only worth 27B or something, he's betting on bitcoin and cryptocurrencies
I don't think it is either a social or political movement, though, so I'm inclined to agree with Buffett.
It's not about Soros opinion. It's about his track record predicting outcomes of political movements and how those impact the money markets.
With BTC is even easier because the price is a sign of the health of the socio-political movement, whereas back in the days he had to rely on the news on the ground about German re-unification or European Union coming together and adopting a common currency.