A 51% attack means a lot of bad things can happen to bitcoin. Its value would probably crash if an individual got 51% of the power just because it is no longer truly decentralized, even if they don't abuse that power.

Bitcoin was made with the idea that a 51% attack would be unlikely and unfeasible; as long as that holds, I'm not sure what value your comparison has. You might as well make a comparison to any other possible disaster. ("A solar flare is a form of state governance that will destroy the value of your coins...")

The top four pools have ~55% of the total hashing power. They could orchestrate a 51% attack with a conference call. As we've seen with the BTH/SegWit2X fiasco, Bitcoin is anything but democratic or decentralised. A cartel is every bit as dangerous as a monopoly.

And what exactly do you think a 51% attack can do? I'll tell you what: censor transactions and make double-spends.

Not exactly end of Bitcoin danger, is it?

If someone had unrestricted ability to double-spend, getting around any attempted countermeasures, they would be able to turn every exchange into a money printing machine. It's hard for me to see how it wouldn't be the end of Bitcoin.

> A 51% attack means a lot of bad things can happen to bitcoin. Its value would probably crash if an individual got 51% of the power just because it is no longer truly decentralized, even if they don't abuse that power.

That already has happened which is why people forked. You can live in denial of that fact if you wish but a minority "lost" the "vote" and forked Bitcoin.

http://fortune.com/2017/08/07/bitcoin-cash-bch-hard-fork-blo...

The BTH/SegWit2X fiasco shows Bitcoin isn't "more" decentralized than an oligopoly, an oligarchy, or a plutocracy.

> Bitcoin was made with the idea that a 51% attack would be unlikely and unfeasible; as long as that holds, I'm not sure what value your comparison has. You might as well make a comparison to any other possible disaster. ("A solar flare is a form of state governance that will destroy the value of your coins...")

The fact pro-bitcoin people swear up and down that isn't the case doesn't change the fact that they are effectively the Bitcoin state and that 2-3 of them + a number of smaller people can effectively "vote" to pass "laws" that are enforced against your BTC regardless of your wishes.

Simply because they don't outright steal your BTC doesn't change the fact you have to comply to retain the value of your BTC.

What does bitcoin cash have to do with a 51% attack? Forks are a different type of thing than 51% attacks.

Why would someone destroy all the value of their money and all the money power to mine just to troll?

Sure a government might do that, but they could point a gun to every full node owners head and tell them to stop it just like China did. It would also be much cheaper.

Step 1: purchase, borrow, or steal enough hash power to reach 51% for a short while

Step 2: use this power to force enough transactions to make yourself rich enough to keep 51% power indefinitely

Step 3: profit

51% hash power lets you doublespend coins. It does not let you steal from wallets or change the block reward rules.

Which is sufficient to allow you to do what I suggested. Spend coin once on paying for everything, and again on yourself to keep all the money to spend again later.

So you become like a government, able to print more currency at will?

According to this definition, is there any possible form of widely-used money that isn’t fiat money?

> According to this definition, is there any possible form of widely-used money that isn’t fiat money?

There used to be 100+ years ago such as gold and silver coins where if you were able to remove them from Country A to Country B, then Country A could no longer enforce such financial penalties against you. This is what many of the cryptocoins _wanted_ to be.

It needs to be a hard currency that leaves you immune to monetary policy and fines unless you are physically within the jurisdiction of the country.