Many thanks for your extensive reply!

With my question above, I was alluding to the fact that a blockchain with higher difficulty is more secure, the lock on the safe is harder to pick.

You raise interesting points, especially regarding network setup/maintenance costs and the deep pockets of some groups. Although I still think it would be cheaper to hijack SHA256 miners if a big player wanted a POW system (loyalty dissolves quickly behind closed doors) miners will work for peanuts compared to establishing a centralised body. And also a widely spatially distributed network is far superior to attack resilience.

My prediction is that we will see a fractional reserve system atop POW crypto before fiat. Miners initially sharing the spoils of the debt repayments (and transaction fees).

But for sure, us "hobbyists" must prepare for larger moves in the game, whatever form they take. To think otherwise is naive.

edit:
a truly anonymous blockchain will never be allowed to flourish.