The $200 million figure in the yearbook is only for “travelling overseers, missionaries and special pioneers”. The cost of keeping 20,000 bethelites and maintaining 80 branches is in addition to the $200 million figure. And then there are publications, digital output, legal fees and other costs on top of that.
Plus another reason for saying Watchtower spends around $2 billion a year is that Lett’s comments indicate revenue of around $2 billion and Lett on another ocassion said there is “more money going out than coming in”. Therefore if revenue is around $2 billion then expenditure is logically at least $2 billion.
I would add that these figures are rendered entirely plausible by a close scrutiny of the figures for the Seventh Day Adventist church which are freely available. They raise and spend even more than JWs. On the one hand that’s suprising because they are from poorer countries and don’t produce as much literature. On the other hand they tithe their members and build school and hospitals and have paid clergy.