From what I can see, they don't spend very much on anything.
Their self-reported number:
During the 2017 service year, * Jehovah’s Witnesses spent over
$202 million in caring for special pioneers, missionaries, and
circuit overseers in their field service assignments.
A lot of that $202M is medical expenses. The WTS is self-insured - any and all medical/dental/vision expenses for any and all of their thousands of "special full time" servants (the ones who take the vow of poverty) are paid in cash directly to the providers. I'm sure they negotiate some favorable rates, but still, it's a huge amount.
Then there are the thousands more of Bethelites, for whom they also pay medical expenses plus food, clothing, and other expenses. They still print millions of pieces of literature as well, granted far less than in other years, but still that's a lot of paper, ink, and machinery maintenance & repair. GBers & their helpers (+ spouses) fly all over the world for "branch visits", "zone visits", international conventions, etc.That's dozens or even hundreds of (business class) flights + hotels + food + transportation per year.
And then of course there are the legal fees. They have a team of "in house" lawyers but there is too much work even for all of them, so they pay standard rates to JW-friendly, or even JW-populated, law firms and individual attorneys. Not to mention who knows how many settlements in civil cases, for child abuse and probably other things (accidents on JW property, for example).
There are no financial statements for us to inspect, of course, but they do burn through a lot of cash every year.