Earlier quoted context omitted.
Bill is wrong. Twitter's revenue per user is quite good. Their problem is that user growth is poor. They can't get enough users to meet their goals. Joi was correct that focusing on users first was the correct decision. They just haven't been able to execute on that goal as well as they hoped for.
There is evidence from past social networks that if you don't hit critical mass of mainstream user adoption, and you've got these lofty valuations, the company is in for a really bad time
Then "money later."