People cite this figure a lot, but its a little misleading because when you own your own servers a lot of the expenses that are typically hosting actually fall under a different category.
If you use AWS, the people hired to manage the servers is part of the price tag. When you own your own you have to actually hire those people.
I mean, it's not like you can get away with running with zero SREs if you're running in the cloud. The personnel costs for on-prem hosting are vastly exaggerated, especially if you contract out the actual annoying work to a colo.
Smart hands is more expensive than having dedicated datacenter staff, and the dedicated staff do a considerably better job. It's worth noting that WMF runs _very_ lean in terms of its datacenter staff.
You're also ignoring the need for infrastructure/network engineers, software engineers, fundraising engineers, product managers, community managers, managers, HR, legal, finance/accounting, fundraisers, etc.
If you use AWS, the people hired to manage the servers is part of the price tag. When you own your own you have to actually hire those people.