I don't think they'd spend it on macadamia nuts for wagyu cows, that's for sure.
Your government is supposed to be elected democratically, so you have some say over it.
Also, the 100bn doesn't even need to be an extra, taxes on other things/ppl could be lowered to have the exact same tax income.
I'm not sure you want to cherrypick this way. I can think of A LOT of stupid things government spends money on, and that's over senators, congresspeople, and lots of government employees.
I don't think you should play this game. Zuckerberg and facebook's personal silly spending is most likely WAY below the stupid things government spends on.
I don't think you want to cherry-pick this way either. A government does infrastructure, military (talk about a moneysink...), space exploration, science, halthcare to some level.