The value is in the network of vendors that trade it. Which is admitedly, very thin and only getting thinner right now.
1) The value may be based on BTC being a payment method. As you said, the group of accepting parties is small and shrinking.
Also, it has to be said that Bitcoin's value is coming from how much it is faster and cheaper than other methods. These methods are improving over time. Bitcoin isn't.
I assume we all understand that if traditional transfers were to catch up - for example simply because they're also based on a distributed ledger (-> J.P. Morgan), value of Bitcoin would be near zero.
2) I said "may be based" earlier, because we don't really know how to value this. I'd assume there have been thousands of attempts all over the world. I've read 3 large publications lately just from this year PhD candidates from my university. It's all theoretical however. We don't even know whether the actual value is lower or higher than current BTC price - let alone by how much.
Yet in the last 7 days big names have said they still think Bitcoin is the future.
Elon Musk said a few days ago Bitcoin is amazing and the future.
CEO of Twitter on Joe Rogan's podcast said he has a lot of Bitcoin and thinks its still the future.
Earlier today the VP of IBM stated Bitcoin is still the future, and he expects it to hit 1 million per coin someday still.
I'd say that Bitcoin (blockchain in general) has been such a hot topic for the last 2 years, that at any given moment in that period you could find 3 important tech managers that said something similar during the previous week.
Also, Elon Musk says whatever he wants to say. The guy doesn't even understand the responsibility he has when talking about companies he owns. Citing him seems pointless.
The anonymous "VP of IBM" you've mentioned is Lund, their Head of Blockchain. I'd assume he is simply fascinated by this subject, so I'm not surprised by his hopes. It's also in his interest to talk about it.
I have such a limited interest in Twitter, that I haven't known who the CEO is until now. I don't know this guy. But he'd be better of focusing on his company's financials.
I think it's worth to notice that all of them are in the tech sector. And we know many tech companies see blockchain as a great new product they could sell. The question is: who will they sell it to? The interest from outside of the tech sector is really slim.
If you've given me 3 names of managers from lets say: General Motors, Tesco and Airbus - talking about Bitcoin, that would be quite amazing.
But this is really funny to watch. Someone important says Bitcoin is the future and the whole crypto community gets a huge orgasm (yes, I've noticed the headlines). Like if this was the first time they've heard it.