OP must have done a lot of research
I found it educative
There are something's I would like to add
They are personal opinion's though
1. Bitcoin hacking is not impossible but so hard that some consider it impossible
2. Bitcoin target was decentralization before security, so POW was used not just for security but since it works better in a decentralized blockchain
3.Bitcoin isn't safe because of developers, Every user of Bitcoin play a role in its security and trust, The miners have their roles, full Nodes, even normal users usage and belief in Bitcoin makes it safe.

These are the few I could think of currently.
Thank you.