The argument that bitcoin should run on a POS network started after top organizations like WEF suggested to lobby 50 key miners to move bitcoin to POS and make change the code not the planet campaign possible. WEF said on their tweet that “change in the way bitcoin is coded could almost eliminate its environmental impact". However, the campaign spearheaded by Ripple co-founder Chris Larsen is expected to fail since some people argue that nodes controls the network not miners because nodes validates and miners propose blocks.
Through 51 percent attack the miners can get hold of the network and control the network but, it's unlikely to launch the 51 percent attack said an article on Investobia as the miners with such hashrate power can get more profits from rewards than launching the attack, More people during the Oslo Freedom forum stated their view about Pow to bitcoin.
Bitcoin needs to have outside contact with the real world that's why the energy is required to mine bitcoin. On the other hand, the price of owning a hash is expensive and it removes the middle class from being able to purchase the hash unlike POS that allows more people to stake on the network. While the price of hash remains high it helps the bitcoin from excaping the 51% attack.
Below are some definitions stated on the use of pow on bitcoind during the WEFORUM
1) So anything that lives on top of this #Bitcoin network will be better than the legacy system that it replaces. And it is only because of PoW that you’re able to have this immutable ledger and all the other layers for financial and economical freedom. Said Darin Feistein
2)Energy serves a very important role. It minimizes human governance.
If you remove the energy component, you’re recreating the legacy system but on a blockchain. Said; Lyn Alden
3) PoW allows everyone to decide on the correct ledger state with no human oversight or governance.
PoS is just a fancy way of referring to shareholder governance or a stakeholder-led system where ownership in the system determines authority in the system. Said; Nic Carter.
Regarding the energy consumption of mining bitcoin which was a key point of the Forum's discussion, I think miners should consider working with Oil and Gas companies on wasted energy to reduce flaring.
Source:
https://bitcoinmagazine.com/markets/greenpeace-seeks-to-change-bitcoin-code
https://bitcoinmagazine.com/technical/proof-of-work-vs-proof-of-stake-why-bitcoin-wont-change
https://www.oilandgasiq.com/decarbonization/articles/us-oil-producers-turn-to-crypto-mining-to-reduce-flaring
