Wikimedia employs a lot of people, I personally do not donate because I believe they employ way too many. Also pretty much all costs are already covered by corporate sponsors like Google.
I remember reading though a page where they listed their employees and I remember it was 100+, I wanted to include the link in my comment, buy couldn't find it this time.
So they're getting paid less than the going rate, at least the software engineers are. Interesting.
Have you considered many of them that are on the payroll might have other jobs and so the volume is to make up for the fact that they're not all 40+ hours full time? I think this is much more complicated than we could first expect
Without a breakdown of where the employees are located and their positions, you can't possibly say anyone at Wikimedia is getting paid more or less than the going rate.
'Sponsor' implies some sort of continuing relationship or cross-promotion or consideration received, so it's not very accurate to say Wikipedia has 'corporate sponsors'. The Wikimedia Foundation has received some corporate donations (including from Google), but those are a relatively small portion of their budget compared to tiny individual donations.
100 employees is too many? (70k per person)
* that 140k and 70k include things like healthcare and benefits too, I bet.