No one ever valued WeWork at $47B. Not for one minute of one day. These lofty numbers came exclusively from WeWork's own propaganda.
>In November 2018, SoftBank acquired a warrant to buy up to $3 billion worth of shares in the company by the end of September 2019 at a $42 billion valuation.
Valuation comes from how much stake you buy blown out as if the rest of the shares cost that much. This naturally doesn't make a lot of sense because the price would go up as you bought the rest of the shares. Still the valuation is ball park correct it was just a complete cock-up on the buyers part.