Delegated is not the same as decentralized.
Satoshi created Bitcoin as a proof of concept and didn't actually engineer any of the end game variables in his system. The result did not lead to decentralization. If it wasn't proof of concept, it would have been engineered a specific way from start to finish, but it wasn't, there's far too many loose ends and unaccounted variables.
True. He clearly left an unfinished development for reasons unknown.
It's unknown if he was even adamant on forcing the system to run on PoW forever. He seems like a relatively smart person, so I kind of doubt he would purposely engineer a system to consume something like one fourth the world's power if it became world reserve currency on purpose.
That's clearly not the case since the block rewards go to zero and the bigger question is whether there would even be enough PoW, not whether there would be too much.
The concern over PoW going gray goo over all the world's power is based on the bizarre premise of moonstruck fanatics that it becomes the world reserve currency
tomorrow, despite not even being able to figure out how to scale above 5-7 tps. After a few more block halvings this would not be the case at all.
Here's a chart showing energy use assuming 1 BTC = $100 000. World electricity production is in the neighborhood of 2 TW, so anything after the first few eras is not particularly problematic.
Original target Subsidy Est Fees Power
Era starting year BTC/block BTC/hour GW
--- --------------- ----------- ---------- ------
0 2009 50.00000000 0.00000000 270.00
1 2013 25.00000000 0.00000000 135.00
2 2017 12.50000000 0.00000000 67.50
3 2021 6.25000000 0.00000000 33.75
4 2025 3.12500000 0.00000000 16.88
5 2029 1.56250000 0.00000000 8.44
6 2033 0.78125000 1.31250000 5.40
7 2037 0.39062500 3.65625000 5.40
8 2041 0.19531250 4.82812500 5.40
9 2045 0.09765625 5.41406250 5.40