[benatkin]

I remember when I thought FlappyCoin was going to be as big as Dogecoin. Nope! I wonder what happens with a devalued Altcoin. I read through the article and the gist seems to be that a 51% attack is possible. I wonder if this has been pulled off with any that were at one time popular. If I were a flappycoin millionaire it would bother me if someone had taken my coins even if they had no monetary value. I imagine some others would be more annoyed than I would be.

[oconnor663]

People have pulled off 51% attacks on altcoins that were arguably popular at the time, most notably Bitcoin Gold. However, note that a successful 51% attack doesn't allow the attacker to steal arbitrary balances. What it mainly allows them to do is to undo their own spending, which they can exploit to commit fraud on exchanges in the short term.

[kpcyrd]

This is the correct threat of a 51% attack, although if the currency is unpopular enough, had little use and everybody stopped mining, you could theoretically fork from the genesis block and replace the whole chain as soon as your fork becomes longer than the original chain.

There is little to gain from attacking a system _that_ unpopular, but you could "take" everybody's coins in that scenario.

[therein]

That's beyond a 51% attack, though. You'd have to have much higher hash rate than that to catch up to the chaintip from scratch as you mine.

[oconnor663]

That's a good point, I never thought about it that way.