Not much of their budget is going toward hosting though -- in FY 18-19 it was ~$2.3M of their ~$91.4M expenses [1].
If we look back to 2005, Wikipedia was already one of the most popular websites on the internet, but their expenses were only $716k [2]. They were frugal back then!
I agree with the parent that the extra expenses are mostly superfluous. They have a ton of staff [3] and quite a few of their roles seem to be about promoting their brand or maximizing donations.