> if your core business function depends on some capability, you should own it

I fear this is easy to misconstrue.

For example, I was at a company that, as I learned how everything worked, realized that we were spending $20k / month for cloud services to basically process about as much real-time data as a CD player processes.

I joked that we should be able to run our entire product on a single server running in the office. (Then I pointed out that this was a joke and that running in the cloud gave us amazing redundancy that we didn't have to implement ourselves.) My point was to show that our architecture was massively bloated and overengineered for what we were doing. (IE, the cost of serialization to send messages was more than the actual processing that was happening. The cost was both money, and the fact that we were spending more time working on messaging than the actual product.)

BUT: There's many times where we could easily say, "this would be so much easier if we had our own server in the office." And, if we misconstrue the above quote, we could convince ourselves to run our own server in the office.