Even in Germany you won't get an engineer for only $5k/month. You can get bad engineers in places like India for that, but good engineers cost more than that.
When you have salaried staff, it's very easy to ignore their cost when they do various background work because it seems to happen for "free." That's not to say that cloud services are always a good value but it's also the case that it's easy to ignore the full cost of doing everything in-house.
German companies for all their precision probably make more than one spending mistake, like we do over here.
There's asymmetry you aren't considering: one engineer can make/solve many problems. Not even all on either side.
To be clear: I'm not taking a dig at this specific case. Larger patterns. It's more nuanced than X of these or Y of those. I'm not arguing in your vacuum/hypothetical
There need-not be an increase in staff in a lot of cases. Just better, or different, staff. If I wanted to earnestly dissect/solve this I wouldn't have opened with snide jokes.
The engineers hired to stave expense tend to go on to create it
The positive spin is: 'get the engineers anyway, self-hosted or not'. They'll help you optimize $solution. My point is things are rarely this positive. Things can be optimized to the point of being non-optimal.