We use the term "extended Bitcoin network" to refer to the overall network that includes the bitcoin P2P protocol, pool-mining protocols, the Stratum protocol, and any other related protocols connecting the components of the Bitcoin system.
Lightening then could be considered "extended Bitcoin Network"?
So, those with more stake in the network are deemed to be more trustworthy, and considered less likely to attack the network. Indeed, in order to mount an attack, a user would have to buy 51% of the coin value of the entire network. This would be expensive, as well as nonsensical — there is no incentive for a user to attack a network in which he has so much invested. Attacking oneself is clearly an illogical action to pursue.
What if the attack it's perform only for a deshonest purpose, with malicious intent, without any economic incentive?
What’s more, mining is a costly endeavor. Some estimates put the electricity consumption costs of the entire Bitcoin mining operation in the region of $500 million per year. In fact, one study has equated the entire power consumption of Bitcoin mining to Ireland’s average electricity consumption. And that’s just for Bitcoin — a whole heap of new cryptocurrencies have emerged that utilize some forms of PoW algorithm.
Given the lenght of what Bitcoin it's trying to accomplish (overtake the financial system), the electricity consumption is not unacceptable I would say. In a 2021 study it came out that Bitcoin consumption of electricity is still less than half of the current traditional financial system.
Flawlessly implementing Casper and Proof Of Stake will be critical if Ethereum plans to scale up.
In the POS system you the chances of winning are mainly based on the amount of stake you have, correct? In such case, what stops an individual, let's say, vitalik buterin, to have a monopoly of ether through the amount of coins he hold? It's truly decentralized?
Theoretically speaking, these big mining pools can simply team up with each other and launch a 51% on the bitcoin network.
But what would be the incentive of this mining pools to do so? They all will maybe get a big pay day in BTC, which would be worthless because people will sell all their coins after a 51% attach. Also, they will stay with an enormous stock of ASICs computers that are made to mine BTC, redirected to what? Unlikely they find something as profitable. The incentives pull to the right side.