It's pretty simple.

If you go on clubhouse right now, there is a room where you can hear 1) Some of the VCs that in the potential deal 2) Some of the angels that already invested 3) the reporter that broke the story talking about this news and your exact question.

And on top of that, they're bringing random people up on the stage to give their opinion on the matter.

What other app allows for this kind of discourse to happen at the current time?

(Now regarding the actualy valuation formual/number, thats a different discussion. Valuations are high rn anyways so a 1B for a social app is frankly not surprising. Remember that companies can create new products/pivot, but not create smarter founders or this amount of organic hype)