[dnomad]

It's important to understand that a "51% attack" isn't an attack at all. No algorithm or protocol has been compromised. The system is working exactly as it should. This is a fundamental aspect of all distributed systems: if the majority of the network elects that the state of A is X then that's the state of A. There is no mechanism by which one peer can disagree and override the majority -- unless the majority have also deigned to follow that peer and recognize it as a "leader."

> Any non-colluding ecosystem should have centralized.

Not exactly. There's real laws and borders and market realities that prevent the ultimate centralization of hashpower but what's clear is that centralization is works, centralization is extremely profitable, it's happening and it will continue [1]. Centralization, I would suggest, is the true goal of bitcoin and is the inevitable conclusion.

> So why the pow?

I see what you're getting at but it should be obvious. The miners are paid very, very handsomely not to collude. Bitcoin miners charge fees that are effectively far greater than any centralized authority. They reap billions in profit each year [2] for turning on a bunch of computers and plugging them in. A cynic might say the "proof of work" is a marketing tool to disguise what is really just the mass transfer of wealth to the miners. Certainly, bitcoin holders believe that miners have somehow "earned" these outrageous profits.

[1] https://blockchain.info/pools

[2] http://fortune.com/2018/02/24/bitcoin-mining-bitmain-profits...