It seems they currently (2019-2020) are responsible for 12% of the expenses [1], but I can't find any information as to which percentage of the donations they're responsible for. I wonder if there's a more transparent report for that.
Looking at their donor numbers [2], it suggests that most of the fundraising is still coming from the long tail, from regular people donating online. They only seem to have 17 "major benefactors" and even if we multiply the smallest amount for that tier (50k) by 10x, that still only accounts for 7% of the donations.
According to their 2019 data, the average donation seems to be $15, which suggests Jimbo banner is way more important than the fundraisers.
Of course my assumption might be completely incorrect.
[1] https://wikimediafoundation.org/about/annualreport/2020-annu...
[2] https://wikimediafoundation.org/about/annualreport/2020-annu...
EN Wikipedia has always been where the lion share of attention was focused on (With wikidata and commons coming in second. The other projects get very little love).
Well, side ventures which burn money would explain factor 10, but yeah...
And it's probably questionable if all side ventures are needed or if they could/should have sticked to the core project and developt it with little money.
As mentioned further down: Do you really need 40 fundraiser positions?