So from this information alone, I'm not sure I see the problem.
You have a very large website that I'm sure gets unimaginable amounts of traffic, operating for free and supported by voluntary donations, and their budget is increasing because they've hired engineers to keep the thing running. That all sounds reasonable enough.
So what's the complaint here? Do you think someone is embezzling money, or that they're just stockpiling money for no reason? Do you think that they're spending money in the wrong places, and if so, where you do think they're spending money, and where do you think they should be spending money? I think you need to give me something before I can figure out how to be outraged at all of this.
That's because this is Slashdot and you haven't bothered to actually read TFA.
Improving Wikipedia’s content is not really in the budget. Nearly $20 million goes toward salaries and wages, despite the fact that none of the staff edit Wikipedia as part of their job function. Almost $6 million was spent last year on awards and grants which certainly help produce some content for Wikipedia,but the writers are not typically compensated with anything more than pizza, sandwiches, and soft drinks.
Less than 6% of the WMF budget is spent on Internet hosting even though most people probably believe it’s their biggest expense. Meanwhile, they spend almost as much money (about $2 million) on travel and conferences. There is also a huge bucket for “other operating expenses” totaling nearly $12.5 million — some of which certainly pays for expensive downtown office space in San Francisco.
The WMF staff busy themselves on things that rarely have anything to do with writing, organizing, or exercising editorial discretion over the actual written product of Wikipedia. Instead, the WMF now considers itself a software and technology organization, but ends up doing more harm than good with its software "innovations". The last two software roll-outs — Visual Editor and Media Viewer — were loathed by a wide swath of users. The WMF responded to the community’s rejection of its software by literally forcing it back on the community with a tool called “superprotect”.
It appears that the Wikimedia Foundation has nearly run out of legitimate ways to spend the donors’ money, because much of it ends up in the organization’s savings accounts and bonds, or pays for software programmers who don't really seem to be doing anything worthwhile.