That doesn't include salaries of the people who run it - and WMF doesn't just rent servers from AWS, like it's in fashion now, they run everything by themselves from the bare metal up, and they run it over multiple data centers over the globe. This probably also doesn't include the cost of the hardware (this likely is part of "depreciation and amortization" since the cost of a server usually is amortized over several years).

And if you've been on any of those conferences (it's not hard to get in, there are a lot of people invited) - they aren't exactly luxury affairs, they usually happen in a library or university and constitute of a crowd of geeks sitting in groups arguing or staring at computer screens, or sometimes presenting slides to other geeks. Those aren't exactly lavish affairs. Of course, some people get their hotel bill and travel paid for, but given those people help building such enormous site as Wikipedia, it's not that huge of an expense.