You can't just look at the total expenses, you need to look at what the necessary expenses are. It's easy to create new expenses when you have available money to spend.

Exactly. Which is precisely what has happened.

Please have a look at this table:

https://en.wikipedia.org/wiki/Wikimedia_Foundation#Financial...

Then read this 2013 post from a past Wikimedia VP:

https://lists.wikimedia.org/pipermail/wikimedia-l/2013-March...

So there is a difference between keeping the Wikimedia Foundation organization going and keeping Wikipedia going. Keeping the Wikimedia Foundation going at its current size costs about 10 times as much as just keeping Wikipedia going, under the assumptions of that 2013 post.

You can't use "keep Wikipedia online" indefinitely as a justification for raising ever more money in order to expand. The Wikimedia Foundation should talk far more in its fundraising about what those hundreds of additional people are actually doing, including projects other than Wikipedia, instead of projecting this image of a small raft of people struggling to hold Wikipedia together with duct tape.

"Decades" might be an exaggeration, but certainly several years if they got they spenditures under control.