Companies are worth what people are willing to to pay for them. Softbank was willing to pay an amount most others weren't. In that situation there are 2 options, take the lower price, or wait until the higher price is proved to be justified.

I don't know at what point we can decide that the vision fund isnt, well, visionary. As things stand though, if you have faith in Weworks business model, this seems like a reasonable move.

To be clear, I don't have any particular faith in that business model, but I don't have any money on the line either way.