I should've thought if this. It would probably still work, honestly. Just start fucking invoicing EVERYONE. 
Discussion
But that's... Not theft.
It might, MIGHT be fraud, but... It's not like he walked into FB and demanded cash.
Exactly. Half of everything written is untrue. And everything an agreement. Of course he did nothing wrong. He simply made them an offer and they complied.
I remember story of one guy who edited the template of standard contract with bank and nobody on bank`s side noticed, so they signed it.
Then he demanded bank to fulfill the condition (And I think it was not something totally outraging, just like basic services for free and no chance to end contract from the bank side :D)
Bank get to court, but lost it :DDD